Hydrogen purification devices, components and fuel processing systems containing the same

ABSTRACT

A hydrogen purification device, components thereof, and fuel processors and fuel cell system containing the same. The hydrogen purification devices include an enclosure that contains a separation assembly adapted to receive a mixed gas stream containing hydrogen gas and to produce a stream that contains pure or at least substantially pure hydrogen gas therefrom. The separation assembly includes at least one hydrogen-permeable and/or hydrogen-selective membrane, and in some embodiments includes at least one membrane envelope that includes a pair of generally opposed membrane regions that define a harvesting conduit therebetween and which are separated by a support. The enclosure includes components that are formed from materials having similar or the same coefficients of thermal expansion as the membrane or membranes. In some embodiments, these components include at least a portion of the support, and in some embodiments, these components include at least a portion of the enclosure.

RELATED APPLICATIONS

This application is a continuation of and claims priority to similarlyentitled U.S. patent application Ser. No. 10/086,680, which was filed onFeb. 28, 2002 U.S. Pat. No. 6,569,227 and issued on May 27, 2003 as U.S.Pat. No. 6,569,227. U.S. Pat. No. 6,569,227 is a continuation-in-part ofand claims priority to U.S. patent application Ser. No. 10/067,275,which was filed on Feb. 4, 2002, issued as U.S. Pat. No. 6,562,111 onMay 13, 2003, and is entitled “Hydrogen Purification Devices, Componentsand Fuel Processing Systems Containing the Same,” U.S. patentapplication Ser. No. 09/967,172, which was filed on Sep. 27, 2001,issued as U.S. Pat. No. 6,494,937 on Dec. 17, 2002, and is entitled“Hydrogen Purification Devices, Components and Fuel Processing SystemsContaining the Same,” and U.S. patent application Ser. No. 10/003,164,which was filed on Nov. 14, 2001, issued as U.S. Pat. No. 6,458,189 onOct. 1, 2002, and is entitled “Hydrogen-Selective Metal Membrane Modulesand Method of Forming the Same.” The complete disclosures of theabove-identified patent applications are hereby incorporated byreference for all purposes.

FIELD OF THE INVENTION

The present invention is related generally to the purification ofhydrogen gas, and more specifically to hydrogen purification devices,components and fuel processing and fuel cell systems containing thesame.

BACKGROUND OF THE INVENTION

Purified hydrogen is used in the manufacture of many products includingmetals, edible fats and oils, and semiconductors and microelectronics.Purified hydrogen is also an important fuel source for many energyconversion devices. For example, fuel cells use purified hydrogen and anoxidant to produce an electrical potential. Various processes anddevices may be used to produce the hydrogen gas that is consumed by thefuel cells. However, many hydrogen-production processes produce animpure hydrogen stream, which may also be referred to as a mixed gasstream that contains hydrogen gas. Prior to delivering this stream to afuel cell or stack of fuel cells, the mixed gas stream may be purified,such as to remove undesirable impurities.

SUMMARY OF THE INVENTION

The present invention is directed to hydrogen purification devices,components of hydrogen purification devices, and fuel processing andfuel cell systems that include hydrogen purification devices. Thehydrogen purification devices include an enclosure that contains aseparation assembly adapted to receive a mixed gas stream containinghydrogen gas and to produce a stream that contains pure or at leastsubstantially pure hydrogen gas therefrom. The separation assemblyincludes at least one hydrogen-permeable and/or hydrogen-selectivemembrane, and in some embodiments includes at least one membraneenvelope that includes a pair of generally opposed membrane regions thatdefine a harvesting conduit therebetween and which are separated by asupport. The device includes one or more components that are formed frommaterials having similar or the same coefficients of thermal expansionas the membrane or membranes. In some embodiments, these componentsinclude at least a portion of the support, and in some embodiments,these components include at least a portion of the enclosure.

Many other features of the present invention will become manifest tothose versed in the art upon making reference to the detaileddescription which follows and the accompanying sheets of drawings inwhich preferred embodiments incorporating the principles of thisinvention are disclosed as illustrative examples only.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a hydrogen purification device.

FIG. 2 is a schematic cross-sectional view of a hydrogen purificationdevice having a planar separation membrane.

FIG. 3 is a schematic cross-sectional view of a hydrogen purificationdevice having a tubular separation membrane.

FIG. 4 is a schematic cross-sectional view of another hydrogenpurification device having a tubular separation membrane.

FIG. 5 is a schematic cross-sectional view of another enclosure for ahydrogen purification device constructed according to the presentinvention.

FIG. 6 is a schematic cross-sectional view of another enclosure for ahydrogen purification device constructed according to the presentinvention.

FIG. 7 is a fragmentary cross-sectional detail showing another suitableinterface between components of an enclosure for a purification deviceaccording to the present invention.

FIG. 8 is a fragmentary cross-sectional detail showing another suitableinterface between components of an enclosure for a purification deviceaccording to the present invention.

FIG. 9 is a fragmentary cross-sectional detail showing another suitableinterface between components of an enclosure for a purification deviceaccording to the present invention.

FIG. 10 is a fragmentary cross-sectional detail showing another suitableinterface between components of an enclosure for a purification deviceaccording to the present invention.

FIG. 11 is a top plan view of an end plate for a hydrogen purificationdevice constructed according to the present invention, including thoseshown in FIGS. 1-6.

FIG. 12 is a cross-sectional view of the end plate of FIG. 11.

FIG. 13 is a top plan view of an end plate for a hydrogen purificationdevice constructed according to the present invention, including thoseshown in FIGS. 1-6.

FIG. 14 is a cross-sectional view of the end plate of FIG. 13.

FIG. 15 is a top plan view of an end plate for a hydrogen purificationdevice constructed according to the present invention, including thoseshown in FIGS. 1-6.

FIG. 16 is a cross-sectional view of the end plate of FIG. 15.

FIG. 17 is a top plan view of an end plate for a hydrogen purificationdevice constructed according to the present invention, including thoseshown in FIGS. 1-6.

FIG. 18 is a cross-sectional view of the end plate of FIG. 17.

FIG. 19 is a top plan view of an end plate for an enclosure for ahydrogen purification device constructed according to the presentinvention, including those shown in FIGS. 1-6.

FIG. 20 is a cross-sectional view of the end plate of FIG. 19.

FIG. 21 is a top plan view of an end plate for an enclosure for ahydrogen purification device constructed according to the presentinvention, including those shown in FIGS. 1-6.

FIG. 22 is a side elevation view of the end plate of FIG. 21.

FIG. 23 is an isometric view of the end plate of FIG. 21.

FIG. 24 is a cross-sectional view of the end plate of FIG. 21.

FIG. 25 is a partial cross-sectional side elevation view of an enclosurefor a hydrogen purification device constructed with a pair of the endplates shown in FIGS. 21-24.

FIG. 26 is an isometric view of another hydrogen purification deviceconstructed according to the present invention.

FIG. 27 is a cross-sectional view of the device of FIG. 26.

FIG. 28 is a side elevation view of another end plate for a hydrogenpurification device constructed according to the present invention,including those shown in FIGS. 1-6.

FIG. 29 is a side elevation view of another end plate for a hydrogenpurification device constructed according to the present invention,including those shown in FIGS. 1-6.

FIG. 30 is a side elevation view of another end plate for a hydrogenpurification device constructed according to the present invention,including those shown in FIGS. 1-6.

FIG. 31 is a fragmentary side elevation view of a pair of separationmembranes separated by a support.

FIG. 32 is an exploded isometric view of a membrane envelope constructedaccording to the present invention and including a support in the formof a screen structure having several layers.

FIG. 33 is an exploded isometric view of another membrane envelopeaccording to the present invention.

FIG. 34 is an exploded isometric view of another membrane envelopeconstructed according to the present invention.

FIG. 35 is an exploded isometric view of another membrane envelopeconstructed according to the present invention.

FIG. 36 is a cross-sectional view of a shell for an enclosure for ahydrogen purification device constructed according to the presentinvention with an illustrative membrane frame and membrane module shownin dashed lines.

FIG. 37 is a top plan view of the end plate of FIG. 13 with anillustrative separation membrane and frame shown in dashed lines.

FIG. 38 is a top plan view of the end plate of FIG. 21 with anillustrative separation membrane and frame shown in dashed lines.

FIG. 39 is an exploded isometric view of another hydrogen purificationdevice constructed according to the present invention.

FIG. 40 is a schematic diagram of a fuel processing system that includesa fuel processor and a hydrogen purification device constructedaccording to the present invention.

FIG. 41 is a schematic diagram of a fuel processing system that includesa fuel processor integrated with a hydrogen purification deviceaccording to the present invention.

FIG. 42 is a schematic diagram of another fuel processor that includesan integrated hydrogen purification device constructed according to thepresent invention.

FIG. 43 is a schematic diagram of a fuel cell system that includes ahydrogen purification device constructed according to the presentinvention.

DETAILED DESCRIPTION AND BEST MODE OF THE INVENTION

A hydrogen purification device is schematically illustrated in FIG. 1and generally indicated at 10. Device 10 includes a body, or enclosure,12 that defines an internal compartment 18 in which a separationassembly 20 is positioned. A mixed gas stream 24 containing hydrogen gas26 and other gases 28 is delivered to the internal compartment. Morespecifically, the mixed gas stream is delivered to a mixed gas region 30of the internal compartment and into contact with separation assembly20. Separation assembly 20 includes any suitable structure adapted toreceive the mixed gas stream and to produce therefrom a permeate, orhydrogen-rich, stream. Stream 34 typically will contain pure or at leastsubstantially pure hydrogen gas. However it is within the scope of theinvention that stream 34 may at least initially also include a carrier,or sweep, gas component.

In the illustrated embodiment, the portion of the mixed gas stream thatpasses through the separation assembly enters a permeate region 32 ofthe internal compartment. This portion of the mixed gas stream formshydrogen-rich stream 34, and the portion of the mixed gas stream thatdoes not pass through the separation assembly forms a byproduct stream36, which contains at least a substantial portion of the other gases. Insome embodiments, byproduct stream 36 may contain a portion of thehydrogen gas present in the mixed gas stream. It is also within thescope of the invention that the separation assembly is adapted to trapor otherwise retain at least a substantial portion of the other gases,which will be removed as a byproduct stream as the assembly is replaced,regenerated or otherwise recharged. In FIG. 1, streams 24, 26 and 28 aremeant to schematically represent that each of streams 24, 26 and 28 mayinclude more that one actual stream flowing into or out of device 10.For example, device 10 may receive plural feed streams 24, a singlestream 24 that is divided into plural streams prior to contactingseparation assembly 20, or simply a single stream that is delivered intocompartment 18.

Device 10 is typically operated at elevated temperatures and/orpressures. For example, device 10 may be operated at (selected)temperatures in the range of ambient temperatures up to 700° C. or more.In many embodiments, the selected temperature will be in the range of200° C. and 500° C., in other embodiments, the selected temperature willbe in the range of 250° C. and 400° C. and in still other embodiments,the selected temperature will be 400° C. either 25° C., 50° C. or 75° C.Device 10 may be operated at (selected) pressures in the range ofapproximately 50 psi and 1000 psi or more. In many embodiments, theselected pressure will be in the range of 50 psi and 250 or 500 psi, inother embodiments, the selected pressure will be less than 300 psi orless than 250 psi, and in still other embodiments, the selected pressurewill be 175 psi±either 25 psi, 50 psi or 75 psi. As a result, theenclosure must be sufficiently well sealed to achieve and withstand theoperating pressure.

It should be understood that as used herein with reference to operatingparameters like temperature or pressure, the term “selected” refers todefined or predetermined threshold values or ranges of values, withdevice 10 and any associated components being configured to operate ator within these selected values. For further illustration, a selectedoperating temperature may be an operating temperature above or below aspecific temperature, within a specific range of temperatures, or withina defined tolerance from a specific temperature, such as within 5%, 10%,etc. of a specific temperature.

In embodiments of the hydrogen purification device in which the deviceis operated at an elevated operating temperature, heat needs to beapplied to the device to raise the temperature of the device to theselected operating temperature. For example, this heat may be providedby any suitable heating assembly 42. Illustrative examples of heatingassembly 42 have been schematically illustrated in FIG. 1. It should beunderstood that assembly 42 may take any suitable form, including mixedgas stream 24 itself. Illustrative examples of other suitable heatingassemblies include one or more of a resistance heater, a burner or othercombustion region that produces a heated exhaust stream, heat exchangewith a heated fluid stream other than mixed gas stream 24, etc. When aburner or other combustion chamber is used, a fuel stream is consumedand byproduct stream 36 may form all or a portion of this fuel stream.At 42′ in FIG. 1, schematic representations have been made to illustratethat the heating assembly may deliver the heated fluid stream externaldevice 10, such as within a jacket that surrounds or at least partiallysurrounds the enclosure, by a stream that extends into the enclosure orthrough passages in the enclosure, or by conduction, such as with anelectric resistance heater or other device that radiates or conductselectrically generated heat.

A suitable structure for separation assembly 20 is one or morehydrogen-permeable and/or hydrogen-selective membranes 46. The membranesmay be formed of any hydrogen-permeable material suitable for use in theoperating environment and parameters in which purification device 10 isoperated. Examples of suitable materials for membranes 46 includepalladium and palladium alloys, and especially thin films of such metalsand metal alloys. Palladium alloys have proven particularly effective,especially palladium with 35 wt % to 45 wt % copper, such as a membranethat contains 40 wt % copper. These membranes are typically formed froma thin foil that is approximately 0.001 inches thick. It is within thescope of the present invention, however, that the membranes may beformed from other hydrogen-permeable and/or hydrogen-selectivematerials, including metals and metal alloys other than those discussedabove as well as non-metallic materials and compositions, and that themembranes may have thicknesses that are greater or less than discussedabove. For example, the membrane may be made thinner, with commensurateincrease in hydrogen flux. Examples of suitable mechanisms for reducingthe thickness of the membranes include rolling, sputtering and etching.A suitable etching process is disclosed in U.S. Pat. No. 6,152,995, thecomplete disclosure of which is hereby incorporated by reference for allpurposes. Examples of various membranes, membrane configurations, andmethods for preparing the same are disclosed in U.S. Pat. No. 6,221,117and U.S. Pat. No. 6,319,306, the complete disclosures of which arehereby incorporated by reference for all purposes.

In FIG. 2, illustrative examples of suitable configurations formembranes 46 are shown. As shown, membrane 46 includes a mixed-gassurface 48 which is oriented for contact by mixed gas stream 24, and apermeate surface 50, which is generally opposed to surface 48. Alsoshown at 52 are schematic representations of mounts, which may be anysuitable structure for supporting and/or positioning the membranes orother separation assemblies within compartment 18. The patent and patentapplications incorporated immediately above also disclose illustrativeexamples of suitable mounts 52. At 46′, membrane 46 is illustrated as afoil or film. At 46″, the membrane is supported by an underlying support54, such as a mesh or expanded metal screen or a ceramic or other porousmaterial. At 46′″, the membrane is coated or formed onto or otherwisebonded to a porous member 56. It should be understood that the membraneconfigurations discussed above have been illustrated schematically inFIG. 2 and are not intended to represent every possible configurationwithin the scope of the invention.

For example, although membrane 46 is illustrated in FIG. 2 as having aplanar configuration, it is within the scope of the invention thatmembrane 46 may have non-planar configurations as well. For example, theshape of the membrane may be defined at least in part by the shape of asupport 54 or member 56 upon which the membrane is supported and/orformed. As such, membranes 46 may have concave, convex or othernon-planar configurations, especially when device 10 is operating at anelevated pressure. As another example, membrane 46 may have a tubularconfiguration, such as shown in FIGS. 3 and 4.

In FIG. 3, an example of a tubular membrane is shown in which the mixedgas stream is delivered to the interior of the membrane tube. In thisconfiguration, the interior of the membrane tube defines region 30 ofthe internal compartment, and the permeate region 32 of the compartmentlies external the tube. An additional membrane tube is shown in dashedlines in FIG. 3 to represent graphically that it is within the scope ofthe present invention that device 10 may include more than one membraneand/or more than one mixed-gas surface 48. It is within the scope of theinvention that device 10 may also include more than two membranes, andthat the relative spacing and/or configuration of the membranes mayvary.

In FIG. 4, another example of a hydrogen purification device 10 thatincludes tubular membranes is shown. In this illustrated configuration,device 10 is configured so that the mixed gas stream is delivered intocompartment 18 external to the membrane tube or tubes. In such aconfiguration, the mixed-gas surface of a membrane tube is exterior tothe corresponding permeate surface, and the permeate region is locatedinternal the membrane tube or tubes.

The tubular membranes may have a variety of configurations andconstructions, such as those discussed above with respect to the planarmembranes shown in FIG. 2. For example, illustrative examples of variousmounts 52, supports 54 and porous members 56 are shown in FIGS. 3 and 4,including a spring 58, which has been schematically illustrated. It isfurther within the scope of the invention that tubular membranes mayhave a configuration other than the straight cylindrical tube shown inFIG. 3. Examples of other configurations include U-shaped tubes andspiral or helical tubes.

As discussed, enclosure 12 defines a pressurized compartment 18 in whichseparation assembly 20 is positioned. In the embodiments shown in FIGS.2-4, enclosure 12 includes a pair of end plates 60 that are joined by aperimeter shell 62. It should be understood that device 10 has beenschematically illustrated in FIGS. 2-4 to show representative examplesof the general components of the device without intending to be limitedto geometry, shape and size. For example, end plates 60 typically arethicker than the walls of perimeter shell 62, but this is not required.Similarly, the thickness of the end plates may be greater than, lessthan or the same as the distance between the end plates. As a furtherexample, the thickness of membrane 46 has been exaggerated for purposesof illustration.

In FIGS. 2-4, it can be seen that mixed gas stream 24 is delivered tocompartment 18 through an input port 64, hydrogen-rich (or permeate)stream 34 is removed from device 10 through one or more product ports66, and the byproduct stream is removed from device 10 through one ormore byproduct ports 68. In FIG. 2, the ports are shown extendingthrough various ones of the end plates to illustrate that the particularlocation on enclosure 12 from which the gas streams are delivered to andremoved from device 10 may vary. It is also within the scope of theinvention that one or more of the streams may be delivered or withdrawnthrough shell 62, such as illustrated in dashed lines in FIG. 3. It isfurther within the scope of the invention that ports 64, 66 and 68 mayinclude or be associated with flow-regulating and/or couplingstructures. Examples of these structures include one or more of valves,flow and pressure regulators, connectors or other fittings and/ormanifold assemblies that are configured to permanently or selectivelyfluidly interconnect device 10 with upstream and downstream components.For purposes of illustration, these flow-regulating and/or couplingstructures are generally indicated at 70 in FIG. 2. For purposes ofbrevity, structures 70 have not been illustrated in every embodiment.Instead, it should be understood that some or all of the ports for aparticular embodiment of device 10 may include any or all of thesestructures, that each port does not need to have the same, if any,structure 70, and that two or more ports may in some embodiments shareor collectively utilize structure 70, such as a common collection ordelivery manifold, pressure relief valve, fluid-flow valve, etc.

End plates 60 and perimeter shell 62 are secured together by a retentionstructure 72. Structure 72 may take any suitable form capable ofmaintaining the components of enclosure 12 together in a fluid-tight orsubstantially fluid-tight configuration in the operating parameters andconditions in which device 10 is used. Examples of suitable structures72 include welds 74 and bolts 76, such as shown in FIGS. 2 and 3. InFIG. 3, bolts 76 are shown extending through flanges 78 that extend fromthe components of enclosure 12 to be joined. In FIG. 4, bolts 76 areshown extending through compartment 18. It should be understood that thenumber of bolts may vary, and typically will include a plurality ofbolts or similar fastening mechanisms extending around the perimeter ofenclosure 12. Bolts 76 should be selected to be able to withstand theoperating parameters and conditions of device 10, including the tensionimparted to the bolts when device 10 is pressurized.

In the lower halves of FIGS. 3 and 4, gaskets 80 are shown to illustratethat enclosure 12 may, but does not necessarily, include a seal member82 interconnecting or spanning the surfaces to be joined to enhance theleak-resistance of the enclosure. The seal member should be selected toreduce or eliminate leaks when used at the operating parameters andunder the operating conditions of the device. Therefore, in manyembodiments, high-pressure and/or high-temperature seals should beselected. An illustrative, non-exclusive example of such a sealstructure is a graphite gasket, such as sold by Union Carbide under thetrade name GRAFOIL™. As used herein, “seal member” and “sealing member”are meant to refer to structures or materials applied to, placedbetween, or placed in contact with the metallic end plates and shell (orshell portions) to enhance the seal established therebetween. Gaskets orother sealing members may also be used within compartment 18, such as toprovide seals between adjacent membranes, fluid conduits, mounts orsupports, and/or any of the above with the internal surface of enclosure12.

In FIGS. 2-4, the illustrated enclosures include a pair of end plates 60and a shell 62. With reference to FIG. 4, it can be seen that the endplates include sealing regions 90, which form an interface 94 with acorresponding sealing region 92 of shell 62. In many embodiments, thesealing region of end plate 60 will be a perimeter region, and as such,sealing region 90 will often be referred to herein as a perimeter region90 of the end plate. However, as used herein, the perimeter region ismeant to refer to the region of the end plate that extends generallyaround the central region and which forms an interface with a portion ofthe shell, even if there are additional portions or edges of the endplate that project beyond this perimeter portion. Similarly, sealingregion 92 of shell 62 will typically be an end region of the shell.Accordingly, the sealing region of the shell will often be referred toherein as end region 92 of the shell. It is within the scope of theinvention, however, that end plates 60 may have portions that projectoutwardly beyond the sealing region 90 and interface 94 formed withshell 62, and that shell 62 may have regions that project beyond endplate 60 and the interface formed therewith. These portions areillustrated in dashed lines in FIG. 4 at 91 and 93 for purposes ofgraphical illustration.

As an alternative to a pair of end plates 60 joined by a separateperimeter shell 62, enclosure 12 may include a shell that is at leastpartially integrated with either or both of the end plates. For example,in FIG. 5, a portion 63 of shell 62 is integrally formed with each endplate 60. Described another way, each end plate 60 includes shellportions, or collars, 63 that extend from the perimeter region 90 of theend plate. As shown, the shell portions include end regions 92 whichintersect at an interface 94. In the illustrated embodiment, the endregions abut each other without a region of overlap; however, it iswithin the scope of the invention that interface 94 may have otherconfigurations, such as those illustrated and/or described subsequently.End regions 92 are secured together via any suitable mechanism, such asby any of the previously discussed retention structures 72, and may (butdo not necessarily) include a seal member 82 in addition to the matingsurfaces of end regions 92.

A benefit of shell 62 being integrally formed with at least one of theend plates is that the enclosure has one less interface that must besealed. This benefit may be realized by reduced leaks due to the reducednumber of seals that could fail, fewer components, and/or a reducedassembly time for device 10. Another example of such a construction forenclosure 12 is shown in FIG. 6, in which the shell 62 is integrallyformed with one of the end plates, with a shell portion 63 that extendsintegrally from the perimeter region 90 of one of the end plates. Shellportion 63 includes an end region 92 that forms an interface 94 with theperimeter region 90 of the other end plate via any suitable retentionstructure 72, such as those described above. The combined end plate andshell components shown in FIGS. 5 and 6 may be formed via any suitablemechanism, including machining them from a solid bar or block ofmaterial. For purposes of simplicity, separation assembly 20 and theinput and output ports have not been illustrated in FIGS. 5 and 6 andonly illustrative, non-exclusive examples of suitable retentionstructure 72 are shown. Similar to the other enclosures illustrated anddescribed herein, it should be understood that the relative dimensionsof the enclosure may vary and still be within the scope of theinvention. For example, shell portions 63 may have lengths that arelonger or shorter than those illustrated in FIGS. 5 and 6.

Before proceeding to additional illustrative configurations for endplates 60, it should be clarified that as used herein in connection withthe enclosures of devices 10, the term “interface” is meant to refer tothe interconnection and sealing region that extends between the portionsof enclosure 12 that are separately formed and thereafter securedtogether, such as (but not necessarily) by one of the previouslydiscussed retention structures 72. The specific geometry and size ofinterface 94 will tend to vary, such as depending upon size,configuration and nature of the components being joined together.Therefore, interface 94 may include a metal-on-metal seal formed betweencorresponding end regions and perimeter regions, a metal-on-metal sealformed between corresponding pairs of end regions, a metal-gasket (orother seal member 82)-metal seal, etc. Similarly, the interface may havea variety of shapes, including linear, arcuate and rectilinearconfigurations that are largely defined by the shape and relativeposition of the components being joined together.

For example, in FIG. 6, an interface 94 extends between end region 92 ofshell portion 63 and perimeter region 90 of end plate 60. As shown,regions 90 and 92 intersect with parallel edges. As discussed, a gasketor other seal member may extend between these edges. In FIGS. 7-10,nonexclusive examples of additional interfaces 94 that are within thescope of the invention are shown. Embodiments of enclosure 12 thatinclude an interface 94 formed between adjacent shell regions may alsohave any of these configurations. In FIG. 7, perimeter region 90 definesa recess or corner into which end region 92 of shell 62 extends to forman interface 94 that extends around this corner. Also shown in FIG. 7 iscentral region 96 of end plate 60, which as illustrated extends withinshell 62 and defines a region of overlap therewith.

In FIG. 8, perimeter region 90 defines a corner that opens generallytoward compartment 18, as opposed to the corner of FIG. 7, which opensgenerally away from compartment 18. In the configuration shown in FIG.8, perimeter region 90 includes a collar portion 98 that extends atleast partially along the outer surface 100 of shell 62 to define aregion of overlap therewith. Central region 96 of plate 60 is shown insolid lines extending along end region 92 without extending into shell62, in dashed lines extending into shell 62, and in dash-dot linesincluding an internal support 102 that extends at least partially alongthe inner surface 104 of shell 60. FIGS. 9 and 10 are similar to FIGS. 7and 8 except that perimeter region 90 and end region 92 are adapted tothreadingly engage each other, and accordingly include correspondingthreads 106 and 108. In dashed lines in FIG. 9, an additional example ofa suitable configuration for perimeter region 90 of end plate 60 isshown. As shown, the outer edge 110 of the end plate does not extendradially (or outwardly) to or beyond the exterior surface of shell 62.

It should be understood that any of these interfaces may be used with anenclosure constructed according to the present invention. However, forpurposes of brevity, every embodiment of enclosure 12 will not be shownwith each of these interfaces. Therefore, although the subsequentlydescribed end plates shown in FIGS. 11-31 are shown with the interfaceconfiguration of FIG. 7, it is within the scope of the invention thatthe end plates and corresponding shells may be configured to have any ofthe interfaces described and/or illustrated herein, as well as theintegrated shell configuration described and illustrated with respect toFIGS. 5 and 6. Similarly, it should be understood that the devicesconstructed according to the present invention may have any of theenclosure configurations, interface configurations, retention structureconfigurations, separation assembly configurations, flow-regulatingand/or coupling structures, seal member configurations, and portconfigurations discussed, described and/or incorporated herein.Similarly, although the following end plate configurations areillustrated with circular perimeters, it is within the scope of theinvention that the end plates may be configured to have perimeters withany other geometric configuration, including arcuate, rectilinear, andangular configurations, as well as combinations thereof.

As discussed, the dimensions of device 10 and enclosure 12 may alsovary. For example, an enclosure designed to house tubular separationmembranes may need to be longer (i.e. have a greater distance betweenend plates) than an enclosure designed to house planar separationmembranes to provide a comparable amount of membrane surface areaexposed to the mixed gas stream (i.e., the same amount of effectivemembrane surface area). Similarly, an enclosure configured to houseplanar separation membranes may tend to be wider (i.e., have a greatercross-sectional area measured generally parallel to the end plates) thanan enclosure designed to house tubular separation membranes. However, itshould be understood that neither of these relationships are required,and that the specific size of the device and/or enclosure may vary.Factors that may affect the specific size of the enclosure include thetype and size of separation assembly to be housed, the operatingparameters in which the device will be used, the flow rate of mixed gasstream 24, the shape and configuration of devices such as heatingassemblies, fuel processors and the like with which or within which thedevice will be used, and to some degree, user preferences.

As discussed previously, hydrogen purification devices may be operatedat elevated temperatures and/or pressures. Both of these operatingparameters may impact the design of enclosures 12 and other componentsof the devices. For example, consider a hydrogen purification device 10operated at a selected operating temperature above an ambienttemperature, such as a device operating at 400° C. As an initial matter,the device, including enclosure 12 and separation assembly 20, must beconstructed from a material that can withstand the selected operatingtemperature, and especially over prolonged periods of time and/or withrepeated heating and cooling off cycles. Similarly, the materials thatare exposed to the gas streams preferably are not reactive or at leastnot detrimentally reactive with the gases. An example of a suitablematerial is stainless steel, such as Type 304 stainless steel, althoughothers may be used.

Besides the thermal and reactive stability described above, operatingdevice 10 at a selected elevated temperature requires one or moreheating assemblies 42 to heat the device to the selected operatingtemperature. When the device is initially operated from a shutdown, orunheated, state, there will be an initial startup or preheating periodin which the device is heated to the selected operating temperature.During this period, the device may produce a hydrogen-rich stream thatcontains more than an acceptable level of the other gases, ahydrogen-rich stream that has a reduced flow rate compared to thebyproduct stream or streams (meaning that a greater percentage of thehydrogen gas is being exhausted as byproduct instead of product), oreven no hydrogen-rich stream at all. In addition to the time to heat thedevice, one must also consider the heat or thermal energy required toheat the device to the selected temperature. The heating assembly orassemblies may add to the operating cost, materials cost, and/orequipment cost of the device. For example, a simplified end plate 60 isa relatively thick slab having a uniform thickness. In fact, Type 304stainless steel plates having a uniform thickness of 0.5″ or 0.75 incheshave proven effective to support and withstand the operating parametersand conditions of device 10. However, the dimensions of these plates addconsiderable weight to device 10, and in many embodiments requireconsiderable thermal energy to be heated to the selected operatingtemperature. As used herein, the term “uniform thickness” is meant torefer to devices that have a constant or at least substantially constantthickness, including those that deviate in thickness by a few (less than5%) along their lengths. In contrast, and as used herein, a “variablethickness” will refer to a thickness that varies by at least 10%, and insome embodiments at least 25%, 40% or 50%.

The pressure at which device 10 is operated may also affect the designof device 10, including enclosure 12 and separation assembly 20.Consider for example a device operating at a selected pressure of 175psi. Device 10 must be constructed to be able to withstand the stressesencountered when operating at the selected pressure. This strengthrequirement affects not only the seals formed between the components ofenclosure 12, but also the stresses imparted to the componentsthemselves. For example, deflection or other deformation of the endplates and/or shell may cause gases within compartment 18 to leak fromthe enclosure. Similarly, deflection and/or deformation of thecomponents of the device may also cause unintentional mixing of two ormore of gas streams 24, 34 and 36. For example, an end plate may deformplastically or elastically when subjected to the operating parametersunder which device 10 is used. Plastic deformation results in apermanent deformation of the end plate, the disadvantage of whichappears fairly evident. Elastic deformation, however, also may impairthe operation of the device because the deformation may result ininternal and/or external leaks. More specifically, the deformation ofthe end plates or other components of enclosure 12 may enable gases topass through regions where fluid-tight seals previously existed. Asdiscussed, device 10 may include gaskets or other seal members to reducethe tendency of these seals to leak, however, the gaskets have a finitesize within which they can effectively prevent or limit leaks betweenopposing surfaces. For example, internal leaks may occur in embodimentsthat include one or more membrane envelopes or membrane platescompressed (with or without gaskets) between the end plates. As the endplates deform and deflect away from each other, the plates and/orgaskets may in those regions not be under the same tension orcompression as existed prior to the deformation. Gaskets, or gasketplates, may be located between a membrane envelope and adjacent feedplates, end plates, and/or other adjacent membrane envelopes. Similarly,gaskets or gasket plates may also be positioned within a membraneenvelope to provide additional leak prevention within the envelope.

In view of the above, it can be seen that there are two or threecompeting factors to be weighed with respect to device 10. In thecontext of enclosure 12, the heating requirements of the enclosure willtend to increase as the materials used to form the enclosure arethickened. To some degree using thicker materials may increase thestrength of the enclosure, however, it may also increase the heating andmaterial requirements, and in some embodiments actually produce regionsto which greater stresses are imparted compared to a thinner enclosure.Areas to monitor on an end plate include the deflection of the endplate, especially at the perimeter regions that form interface(s) 94,and the stresses imparted to the end plate.

Consider for example a circular end plate formed from Type 304 stainlesssteel and having a uniform thickness of 0.75 inches. Such an end plateweights 7.5 pounds. A hydrogen purification device containing this endplate was exposed to operating parameters of 400° C. and 175 psi.Maximum stresses of 25,900 psi were imparted to the end plate, with amaximum deflection of 0.0042 inches and a deflection at perimeter region90 of 0.0025 inches.

Another end plate 60 constructed according to the present invention isshown in FIGS. 11 and 12 and generally indicated at 120. As shown, endplate 120 has interior and exterior surfaces 122 and 124. Interiorsurface 122 includes central region 96 and perimeter region 90. Exteriorsurface 124 has a central region 126 and a perimeter region 128, and inthe illustrated embodiment, plate 120 has a perimeter 130 extendingbetween the perimeter regions 90 and 128 of the interior and exteriorsurfaces. As discussed above, perimeter region 90 may have any of theconfigurations illustrated or described above, including a configurationin which the sealing region is at least partially or completely locatedalong perimeter 130. In the illustrated embodiment, perimeter 130 has acircular configuration. However, it is within the scope of the inventionthat the shape may vary, such as to include rectilinear and otherarcuate, geometric, linear, and/or cornered configurations.

Unlike the previously illustrated end plates, however, the centralregion of the end plate has a variable thickness between its interiorand exterior surfaces, which is perhaps best seen in FIG. 12. Unlike auniform slab of material, the exterior surface of plate 120 has acentral region 126 that includes an exterior cavity, or removed region,132 that extends into the plate and generally toward central region 96on interior surface 122. Described another way, the end plate has anonplanar exterior surface, and more specifically, an exterior surfacein which at least a portion of the central region extends toward thecorresponding central region of the end plate's interior surface. Region132 reduces the overall weight of the end plate compared to a similarlyconstructed end plate that does not include region 132. As used herein,removed region 132 is meant to exclude ports or other bores that extendcompletely through the end plates. Instead, region 132 extends into, butnot through, the end plate.

A reduction in weight means that a purification device 10 that includesthe end plate will be lighter than a corresponding purification devicethat includes a similarly constructed end plate formed without region132. With the reduction in weight also comes a corresponding reductionin the amount of heat (thermal energy) that must be applied to the endplate to heat the end plate to a selected operating temperature. In theillustrated embodiment, region 132 also increases the surface area ofexterior surface 124. Increasing the surface area of the end platecompared to a corresponding end plate may, but does not necessarily inall embodiments, increase the heat transfer surface of the end plate,which in turn, can reduce the heating requirements and/or time of adevice containing end plate 120.

In some embodiments, plate 120 may also be described as having a cavitythat corresponds to, or includes, the region of maximum stress on asimilarly constructed end plate in which the cavity was not present.Accordingly, when exposed to the same operating parameters andconditions, lower stresses will be imparted to end plate 120 than to asolid end plate formed without region 132. For example, in the solid endplate with a uniform thickness, the region of maximum stress occurswithin the portion of the end plate occupied by removed region 132 inend plate 120. Accordingly, an end plate with region 132 mayadditionally or alternatively be described as having a stress abatementstructure 134 in that an area of maximum stress that would otherwise beimparted to the end plate has been removed.

For purposes of comparison, consider an end plate 120 having theconfiguration shown in FIGS. 11 and 12, formed from Type 304 stainlesssteel, and having a diameter of 6.5 inches. This configurationcorresponds to maximum plate thickness of 0.75 inches and a removedregion 132 having a length and width of 3 inches. When utilized in adevice 10 operating at 400° C. and 175 psi, plate 120 has a maximumstress imparted to it of 36,000 psi, a maximum deflection of 0.0078inches, a displacement of 0.0055 inches at perimeter region 90, and aweight of 5.7 pounds. It should be understood that the dimensions andproperties described above are meant to provide an illustrative exampleof the combinations of weight, stress and displacement experienced byend plates according to the present invention, and that the specificperimeter shape, materials of construction, perimeter size, thickness,removed region shape, removed region depth and removed region perimeterall may vary within the scope of the invention.

In FIG. 11, it can be seen that region 132 (and/or stress abatementstructure 134) has a generally square or rectilinear configurationmeasured transverse to surfaces 122 and 124. As discussed, othergeometries and dimensions may be used and are within the scope of theinvention. To illustrate this point, variations of end plate 120 areshown in FIGS. 13-16 and generally indicated at 120′ and 120″. In thesefigures, region 132 is shown having a circular perimeter, with thedimensions of the region being smaller in FIGS. 13 and 14 than in FIGS.15 and 16.

For purposes of comparison, consider an end plate 120 having theconfiguration shown in FIGS. 13 and 14 and having the same materials ofconstruction, perimeter and thickness as the end plate shown in FIGS. 11and 12. Instead of the generally square removed region of FIGS. 11 and12, however, end plate 120′ has a removed region with a generallycircular perimeter and a diameter of 3.25 inches. End plate 120′ weighsthe same as end plate 120, but has reduced maximum stress anddeflections. More specifically, while end plate 120 had a maximum stressgreater than 35,000 psi, end plate 120′ had a maximum stress that isless than 30,000 psi, and in the illustrated configuration less than25,000 psi, when subjected to the operating parameters discussed abovewith respect to plate 120. In fact, plate 120′ demonstratedapproximately a 35% reduction in maximum stress compared to plate 120.The maximum and perimeter region deflections of plate 120′ were alsoless than plate 120, with a measured maximum deflection of 0.007 inchesand a measured deflection at perimeter region 90 of 0.0050 inches.

End plate 120″, which is shown in FIGS. 15 and 16 is similar to endplate 120′, except region 132 (and/or structure 134) has a diameter of3.75 inches instead of 3.25 inches. This change in the size of theremoved region decreases the weight of the end plate to 5.3 pounds andproduced the same maximum deflection. End plate 120″ also demonstrated amaximum stress that is less than 25,000 psi, although approximately 5%greater than that of end plate 120′ (24,700 psi, compared to 23,500psi). At perimeter region 90, end plate 120″ exhibited a maximumdeflection of 0.0068 inches.

In FIGS. 13-16, illustrative port configurations have been shown. InFIGS. 13 and 14, a port 138 is shown in dashed lines extending frominterior surface 122 through the end plate to exterior surface 124.Accordingly, with such a configuration a gas stream is delivered orremoved via the exterior surface of the end plate of device 10. In sucha configuration, fluid conduits and/or flow-regulating and/or couplingstructure 70 typically will project from the exterior surface 124 of theend plate. Another suitable configuration is indicated at 140 in dashedlines in FIGS. 15 and 16. As shown, port 140 extends from the interiorsurface of the end plate then through perimeter 130 instead of exteriorsurface 124. Accordingly, port 140 enables gas to be delivered orremoved from the perimeter of the end plate instead of the exteriorsurface of the end plate. It should be understood that ports 64-68 mayhave these configurations illustrated by ports 138 and 140. Of course,ports 64-68 may have any other suitable port configuration as well,including a port that extends through shell 62 or a shell portion. Forpurposes of simplicity, ports will not be illustrated in many of thesubsequently described end plates, just as they were not illustrated inFIGS. 5 and 6.

Also shown in dashed lines in FIGS. 13-15 are guide structures 144.Guide structures 144 extend into compartment 18 and provide supportsthat may be used to position and/or align separation assembly 20, suchas membranes 46. In some embodiments, guide structures 144 maythemselves form mounts 52 for the separation assembly. In otherembodiments, the device includes mounts other than guide structures 144.Guide structures may be used with any of the end plates illustrated,incorporated and/or described herein, regardless of whether any suchguide structures are shown in a particular drawing figure. However, itshould also be understood that hydrogen purification devices accordingto the present invention may be formed without guide structures 144. Inembodiments of device 10 that include guide structures 144 that extendinto or through compartment 18, the number of such structures may varyfrom a single support to two or more supports. Similarly, while guidestructures 144 have been illustrated as cylindrical ribs or projections,other shapes and configurations may be used within the scope of theinvention.

Guide structures 144 may be formed from the same materials as thecorresponding end plates. Additionally or alternatively, the guidestructures may include a coating or layer of a different material. Guidestructures 144 may be either separately formed from the end plates andsubsequently attached thereto, or integrally formed therewith. Guidestructures 144 may be coupled to the end plates by any suitablemechanism, including attaching the guide structures to the interiorsurfaces of the end plates, inserting the guide structures into boresextending partially through the end plates from the interior surfacesthereof, or inserting the guide structures through bores that extendcompletely through the end plates. In embodiments where the end platesinclude bores that extend completely through the end plates (which aregraphically illustrated for purposes of illustration at 146 in FIG. 14),the guide structures may be subsequently affixed to the end plates.Alternatively, the guide structures may be inserted through compartment18 until the separation assembly is properly assigned and securedtherein, and then the guide structures may be removed and the boressealed (such as by welding) to prevent leaks.

In FIGS. 17 and 18, another end plate 60 constructed according to thepresent invention is shown and generally indicated at 150. Unlessotherwise specified, it should be understood that end plates 150 mayhave any of the elements, subelements and variations as any of the otherend plates shown, described and/or incorporated herein. Similar to endplate 120′, plate 150 includes an exterior surface 124 with a removedregion 132 (and/or stress abatement structure 134) having a circularperimeter with a diameter of 3.25 inches. Exterior surface 124 furtherincludes an outer removed region 152 that extends from central region126 to perimeter portion 128. Outer removed region 152 decreases inthickness as it approaches perimeter 130. In the illustrated embodiment,region 152 has a generally linear reduction in thickness, although otherlinear and arcuate transitions may be used. For example, a variation ofend plate 150 is shown in FIGS. 19 and 20 and generally indicated at150′. End plate 150′ also includes central and exterior removed regions132 and 152, with exterior surface 124 having a generally semitoroidalconfiguration as it extends from central region 126 to perimeter region128. To demonstrate that the size of region 132 (which will also bereferred to as a central removed region, such as when embodied on an endplate that also includes an outer removed region), may vary, end plate150′ includes a central removed region having a diameter of 3 inches.

For purposes of comparison, both end plates 150 and 150′ have reducedweights compared to end plates 120, 120′ and 120″. Plate 150 weighed 4.7pounds, and plate 150′ weighed 5.1 pounds. Both end plates 150 and 150′experienced maximum stresses of 25,000 psi or less when subjected to theoperating parameters discussed above (400° C. and 175 psi), with plate150′ having a 5% lower stress than plate 150 (23,750 psi compared to25,000 psi). The maximum deflections of the plates were 0.0098 inchesand 0.008 inches, respectively, and the displacements at perimeterregions 90 were 0.0061 inches and 0.0059 inches, respectively.

Another end plate 60 constructed according to the present invention isshown in FIGS. 21-24 and generally indicated at 160. Unless otherwisespecified, end plate 160 may have the same elements, subelements andvariations as the other end plates illustrated, described and/orincorporated herein. End plate 160 may be referred to as atruss-stiffened end plate because it includes a truss assembly 162 thatextends from the end plate's exterior surface 124. As shown, end plate160 has a base plate 164 with a generally planar configuration, similarto the end plates shown in FIGS. 2-5. However, truss assembly 162enables, but does not require, that the base plate may have a thinnerconstruction while still providing comparable if not reduced maximumstresses and deflections. It is within the scope of the invention thatany of the other end plates illustrated, described and/or incorporatedherein also may include a truss assembly 162.

Truss assembly 162 extends from exterior surface 124 of base plate 164and includes a plurality of projecting ribs 166 that extend fromexterior surface 124. In FIGS. 21-24, it can be seen that ribs 166 areradially spaced around surface 124. Nine ribs 166 are shown in FIGS. 21and 23, but it is within the scope of the invention that truss assembly162 may be formed with more or fewer ribs. Similarly, in the illustratedembodiment, ribs 166 have arcuate configurations, and include flanges168 extending between the ribs and surface 124. Flanges 168 may also bedescribed as heat transfer fins because they add considerable heattransfer area to the end plate. Truss assembly 162 further includes atension collar 170 that interconnects the ribs. As shown, collar 170extends generally parallel to surface base plate 164 and has an opencentral region 172. Collar 170 may be formed with a closed or internallyor externally projecting central portion without departing from theinvention. To illustrate this point, members 174 are shown in dashedlines extending across collar 170 in FIG. 21. Similarly, collar 170 mayhave configurations other than the circular configuration shown in FIGS.21-24. As a further alternative, base plate 164 has been indicated inpartial dashed lines in FIG. 22 to graphically illustrate that the baseplate may have a variety of configurations, such as those described,illustrated and incorporated herein, including the configuration shownif the dashed region is removed.

End plate 160 may additionally, or alternatively, be described as havinga support 170 that extends in a spaced-apart relationship beyondexterior surface 124 of base plate 164 and which is adapted to provideadditional stiffness and/or strength to the base plate. Still anotheradditional or alternative description of end plate 160 is that the endplate includes heat transfer structure 162 extending away from theexterior surface of the base plate, and that the heat transfer structureincludes a surface 170 that is spaced-away from surface 124 such that aheated fluid stream may pass between the surfaces.

Truss assembly 162 may also be referred to as an example of a deflectionabatement structure because it reduces the deflection that wouldotherwise occur if base plate 164 were formed without the trussassembly. Similarly, truss assembly 162 may also provide another exampleof a stress abatement restructure because it reduces the maximumstresses that would otherwise be imparted to the base plate.Furthermore, the open design of the truss assembly increases the heattransfer area of the base plate without adding significant weight to thebase plate.

Continuing the preceding comparisons between end plates, plate 160 wassubjected to the same operating parameters as the previously describedend plates. The maximum stresses imparted to base plate 164 were 10,000psi or less. Similarly, the maximum deflection of the base plate wasonly 0.0061 inches, with a deflection of 0.0056 inches at perimeterregion 90. It should be noted, that base plate 160 achieved thissignificant reduction in maximum stress while weighing only 3.3 pounds.Similarly, base plate 164 experienced a smaller maximum displacement andcomparable or reduced perimeter displacement yet had a base plate thatwas only 0.25 inches thick. Of course, plate 160 may be constructed withthicker base plates, but the tested plate proved to be sufficientlystrong and rigid under the operating parameters with which it was used.

As discussed, enclosure 12 may include a pair of end plates 60 and aperimeter shell. In FIG. 25, an example of an enclosure 12 formed with apair of end plates 160 is shown for purposes of illustration andindicated generally at 180. Although enclosure 180 has a pair oftruss-stiffened end plates 160, it is within the scope of the inventionthat an enclosure may have end plates having different constructionsand/or configurations. In fact, in some operating environments it may bebeneficial to form enclosure 12 with two different types of end plates.In others, it may be beneficial for the end plates to have the sameconstruction.

In FIGS. 26 and 27 another example of an enclosure 12 is shown andgenerally indicated at 190 and includes end plates 120′″. End plate120′″ has a configuration similar to FIGS. 13-16, except removed region132 is shown having a diameter of 4 inches to further illustrate thatthe shape and size of the removed region may vary within the scope ofthe invention. Both end plates include shell portions 63 extendingintegrally therefrom to illustrate that any of the end platesillustrated, described, and/or incorporated herein may include a shellportion 63 extending integrally therefrom. To illustrate that any of theend plates described, illustrated and/or incorporated herein may alsoinclude truss assemblies (or heat transfer structure) 162 and/orprojecting supports 170 or deflection abatement structure, members 194are shown projecting across removed region 132 in a spaced-apartconfiguration from the exterior surface 124 of the end plate.

It is also within the scope of the invention that enclosure 12 mayinclude stress and/or deflection abatement structures that extend intocompartment 18 as opposed to, or in addition to, correspondingstructures that extend from the exterior surface of the end plates. InFIGS. 28-30, end plates 60 are shown illustrating examples of thesestructures. For example, in FIG. 28, end plate 60 includes a removedregion 132 that extends into the end plate from the interior surface 122of the end plate. It should be understood that region 132 may have anyof the configurations described, illustrated and/or incorporated hereinwith respect to removed regions that extend from the exterior surface ofa base plate. Similarly, in dashed lines at 170 in FIG. 28, supports areshown extending across region 132 to provide additional support and/orrigidity to the end plate. In FIG. 29, end plate 60 includes internalsupports 196 that are adapted to extend into compartment 18 tointerconnect the end plate with the corresponding end plate at the otherend of the compartment. As discussed, guide structures 144 may form sucha support. In FIG. 30, an internally projecting truss assembly 162 isshown.

Although not required or essential to the invention, in someembodiments, device 10 includes end plates 60 that exhibit at least oneof the following properties or combinations of properties compared to anend plate formed from a solid slab of uniform thickness of same materialas end plate 60 and exposed to the same operating parameters:

a projecting truss assembly;

an internally projecting support;

an externally projecting support;

an external removed region;

an internal removed region;

an integral shell portion;

an integral shell;

a reduced mass and reduced maximum stress;

a reduced mass and reduced maximum displacement;

a reduced mass and reduced perimeter displacement;

a reduced mass and increased heat transfer area;

a reduced mass and internally projecting supports;

a reduced mass and externally projecting supports;

a reduced maximum stress and reduced maximum displacement;

a reduced maximum stress and reduced perimeter displacement;

a reduced maximum stress and increased heat transfer area;

a reduced maximum stress and a projecting truss assembly;

a reduced maximum stress and a removed region;

a reduced maximum displacement and reduced perimeter displacement;

a reduced maximum displacement and increased heat transfer area;

a reduced perimeter displacement and increased heat transfer area;

a reduced perimeter displacement and a projecting truss assembly;

a reduced perimeter displacement and a removed region;

a mass/maximum displacement ratio that is less than 1500 lb/psi;

a mass/maximum displacement ratio that is less than 1000 lb/psi;

a mass/maximum displacement ratio that is less than 750 lb/psi;

a mass/maximum displacement ratio that is less than 500 lb/psi;

a mass/perimeter displacement ratio that is less than 2000 lb/psi;

a mass/perimeter displacement ratio that is less than 1500 lb/psi;

a mass/perimeter displacement ratio that is less than 1000 lb/psi;

a mass/perimeter displacement ratio that is less than 800 lb/psi;

a mass/perimeter displacement ratio that is less than 600 lb/psi;

a cross-sectional area/mass ratio that is at least 6 in²/pound;

a cross-sectional area/mass ratio that is at least 7 in²/pound; and/or

a cross-sectional area/mass ratio that is at least 10 in²/pound.

As discussed, enclosure 12 contains an internal compartment 18 thathouses separation assembly 20, such as one or more separation membranes46, which are supported within the enclosure by a suitable mount 52. Inthe illustrative examples shown in FIGS. 2 and 4, the separationmembranes 46 were depicted as independent planar or tubular membranes.It is also within the scope of the invention that the membranes may bearranged in pairs that define permeate region 32 therebetween. In such aconfiguration, the membrane pairs may be referred to as a membraneenvelope, in that they define a common permeate region 32 in the form ofa harvesting conduit, or flow path, extending therebetween and fromwhich hydrogen-rich stream 34 may be collected.

An example of a membrane envelope is shown in FIG. 31 and generallyindicated at 200. It should be understood that the membrane pairs maytake a variety of suitable shapes, such as planar envelopes and tubularenvelopes. Similarly, the membranes may be independently supported, suchas with respect to an end plate or around a central passage. Forpurposes of illustration, the following description and associatedillustrations will describe the separation assembly as including one ormore membrane envelopes 200. It should be understood that the membranesforming the envelope may be two separate membranes, or may be a singlemembrane folded, rolled or otherwise configured to define two membraneregions, or surfaces, 202 with permeate surfaces 50 that are orientedtoward each other to define a conduit 204 therebetween from which thehydrogen-rich permeate gas may be collected and withdrawn. Conduit 204may itself form permeate region 32, or a device 10 according to thepresent invention may include a plurality of membrane envelopes 200 andcorresponding conduits 204 that collectively define permeate region 32.

To support the membranes against high feed pressures, a support 54 isused. Support 54 should enable gas that permeates through membranes 46to flow therethrough. Support 54 includes surfaces 211 against which thepermeate surfaces 50 of the membranes are supported. In the context of apair of membranes forming a membrane envelope, support 54 may also bedescribed as defining harvesting conduit 204. In conduit 204, permeatedgas preferably may flow both transverse and parallel to the surface ofthe membrane through which the gas passes, such as schematicallyillustrated in FIG. 31. The permeate gas, which is at leastsubstantially pure hydrogen gas, may then be harvested or otherwisewithdrawn from the envelope to form hydrogen-rich stream 34. Because themembranes lie against the support, it is preferable that the supportdoes not obstruct the flow of gas through the hydrogen-selectivemembranes. The gas that does not pass through the membranes forms one ormore byproduct streams 36, as schematically illustrated in FIG. 31.

An example of a suitable support 54 for membrane envelopes 200 is shownin FIG. 32 in the form of a screen structure 210. Screen structure 210includes plural screen members 212. In the illustrated embodiment, thescreen members include a coarse mesh screen 214 sandwiched between finemesh screens 216. It should be understood that the terms “fine” and“coarse” are relative terms. Preferably, the outer screen members areselected to support membranes 46 without piercing the membranes andwithout having sufficient apertures, edges or other projections that maypierce, weaken or otherwise damage the membrane under the operatingconditions with which device 10 is operated. Because the screenstructure needs to provide for flow of the permeated gas generallyparallel to the membranes, it is preferable to use a relatively coarserinner screen member to provide for enhanced, or larger, parallel flowconduits. In other words, the finer mesh screens provide betterprotection for the membranes, while the coarser mesh screen providesbetter flow generally parallel to the membranes and in some embodimentsmay be selected to be stiffer, or less flexible, than the finer meshscreens.

The screen members may be of similar or the same construction, and moreor less screen members may be used than shown in FIG. 32. Preferably,support 54 is formed from a corrosion-resistant material that will notimpair the operation of the hydrogen purification device and otherdevices with which device 10 is used. Examples of suitable materials formetallic screen members include stainless steels, titanium and alloysthereof, zirconium and alloys thereof, corrosion-resistant alloys,including Inconel™ alloys, such as 800H™, and Hastelloy™ alloys, andalloys of copper and nickel, such as Monel™. Hasteloy™ and Inconel™alloys are nickel-based alloys. Inconel™ alloys typically contain nickelalloyed with chromium and iron. Monel™ alloys typically are alloys ofnickel, copper, iron and manganese. Additional examples of structure forsupports 54 include porous ceramics, porous carbon, porous metal,ceramic foam, carbon foam, and metal foam, either alone, or incombination with one or more screen members 212. As another example,some or all of the screen members may be formed from expanded metalinstead of a woven mesh material.

During fabrication of the membrane envelopes, adhesive may be used tosecure membranes 46 to the screen structure and/or to secure thecomponents of screen structure 210 together, as discussed in more detailin the above-incorporated U.S. Pat. No. 6,319,306. For purposes ofillustration, adhesive is generally indicated in dashed lines at 218 inFIG. 32. An example of a suitable adhesive is sold by 3M under the tradename SUPER 77. Typically, the adhesive is at least substantially, if notcompletely, removed after fabrication of the membrane envelope so as notto interfere with the permeability, selectivity and flow paths of themembrane envelopes. An example of a suitable method for removingadhesive from the membranes and/or screen structures or other supportsis by exposure to oxidizing conditions prior to initial operation ofdevice 10. The objective of the oxidative conditioning is to burn outthe adhesive without excessively oxidizing the palladium-alloy membrane.A suitable procedure for such oxidizing is disclosed in theabove-incorporated patent application.

Supports 54, including screen structure 210, may include a coating 219on the surfaces 71 that engage membranes 46, such as indicated indash-dot lines in FIG. 32. Examples of suitable coatings includealuminum oxide, tungsten carbide, tungsten nitride, titanium carbide,titanium nitride, and mixtures thereof. These coatings are generallycharacterized as being thermodynamically stable with respect todecomposition in the presence of hydrogen. Suitable coatings are formedfrom materials, such as oxides, nitrides, carbides, or intermetalliccompounds, that can be applied as a coating and which arethermodynamically stable with respect to decomposition in the presenceof hydrogen under the operating parameters (temperature, pressure, etc.)under which the hydrogen purification device will be operated. Suitablemethods for applying such coatings to the screen or expanded metalscreen member include chemical vapor deposition, sputtering, thermalevaporation, thermal spraying, and, in the case of at least aluminumoxide, deposition of the metal (e.g., aluminum) followed by oxidation ofthe metal to give aluminum oxide. In at least some embodiments, thecoatings may be described as preventing intermetallic diffusion betweenthe hydrogen-selective membranes and the screen structure.

The hydrogen purification devices 10 described, illustrated and/orincorporated herein may include one or more membrane envelopes 200,typically along with suitable input and output ports through which themixed gas stream is delivered and from which the hydrogen-rich andbyproduct streams are removed. In some embodiments, the device mayinclude a plurality of membrane envelopes. When the separation assemblyincludes a plurality of membrane envelopes, it may include fluidconduits interconnecting the envelopes, such as to deliver a mixed gasstream thereto, to withdraw the hydrogen-rich stream therefrom, and/orto withdraw the gas that does not pass through the membranes from mixedgas region 30. When the device includes a plurality of membraneenvelopes, the permeate stream, byproduct stream, or both, from a firstmembrane envelope may be sent to another membrane envelope for furtherpurification. The envelope or plurality of envelopes and associatedports, supports, conduits and the like may be referred to as a membranemodule 220.

The number of membrane envelopes 200 used in a particular device 10depends to a degree upon the feed rate of mixed gas stream 24. Forexample, a membrane module 220 containing four envelopes 200 has proveneffective for a mixed gas stream delivered to device 10 at a flow rateof 20 liters/minute. As the flow rate is increased, the number ofmembrane envelopes may be increased, such as in a generally linearrelationship. For example, a device 10 adapted to receive mixed gasstream 24 at a flow rate of 30 liters/minute may preferably include sixmembrane envelopes. However, these exemplary numbers of envelopes areprovided for purposes of illustration, and greater or fewer numbers ofenvelopes may be used. For example, factors that may affect the numberof envelopes to be used include the hydrogen flux through the membranes,the effective surface area of the membranes, the flow rate of mixed gasstream 24, the desired purity of hydrogen-rich stream 34, the desiredefficiency at which hydrogen gas is removed from mixed gas stream 24,user preferences, the available dimensions of device 10 and compartment18, etc.

Preferably, but not necessarily, the screen structure and membranes thatare incorporated into a membrane envelope 200 include frame members 230,or plates, that are adapted to seal, support and/or interconnect themembrane envelopes. An illustrative example of suitable frame members230 is shown in FIG. 33. As shown, screen structure 210 fits within aframe member 230 in the form of a permeate frame 232. The screenstructure and frame 232 may collectively be referred to as a screenplate or permeate plate 234. When screen structure 210 includes expandedmetal members, the expanded metal screen members may either fit withinpermeate frame 232 or extend at least partially over the surface of theframe. Additional examples of frame members 230 include supportingframes, feed plates and/or gaskets. These frames, gaskets or othersupport structures may also define, at least in part, the fluid conduitsthat interconnect the membrane envelopes in an embodiment of separationassembly 20 that contains two or more membrane envelopes. Examples ofsuitable gaskets are flexible graphite gaskets, including those soldunder the trade name GRAFOIL™ by Union Carbide, although other materialsmay be used, such as depending upon the operating conditions under whichdevice 10 is used.

Continuing the above illustration of exemplary frame members 230,permeate gaskets 236 and 236′ are attached to permeate frame 232,preferably but not necessarily, by using another thin application ofadhesive. Next, membranes 46 are supported against screen structure 210and/or attached to screen structure 210 using a thin application ofadhesive, such as by spraying or otherwise applying the adhesive toeither or both of the membrane and/or screen structure. Care should betaken to ensure that the membranes are flat and firmly attached to thecorresponding screen member 212. Feed plates, or gaskets, 238 and 238′are optionally attached to gaskets 236 and 236′, such as by usinganother thin application of adhesive. The resulting membrane envelope200 is then positioned within compartment 18, such as by a suitablemount 52. Optionally, two or more membrane envelopes may be stacked orotherwise supported together within compartment 18.

As a further alternative, each membrane 46 may be fixed to a framemember 230, such as metal frames 240 and 240′, as shown in FIG. 34. Ifso, the membrane is fixed to the frame, for instance by ultrasonicwelding or another suitable attachment mechanism. The membrane-frameassembly may, but is not required to be, attached to screen structure210 using adhesive. Other examples of attachment mechanisms that achievegas-tight seals between plates forming membrane envelope 200, as well asbetween the membrane envelopes, include one or more of brazing,gasketing, and welding. The membrane and attached frame may collectivelybe referred to as a membrane plate, such as indicated at 242 and 242′ inFIG. 34. It is within the scope of the invention that the various framesdiscussed herein do not all need to be formed from the same materialsand/or that the frames may not have the same dimensions, such as thesame thicknesses. For example, the permeate and feed frames may beformed from stainless steel or another suitable structural member, whilethe membrane plate may be formed from a different material, such ascopper, alloys thereof, and other materials discussed in theabove-incorporated patents and applications. Additionally and/oralternatively, the membrane plate may, but is not required to be,thinner than the feed and/or permeate plates.

For purposes of illustration, a suitable geometry of fluid flow throughmembrane envelope 200 is described with respect to the embodiment ofenvelope 200 shown in FIG. 33. As shown, mixed gas stream 24 isdelivered to the membrane envelope and contacts the outer surfaces 50 ofmembranes 46. The hydrogen-rich gas that permeates through the membranesenters harvesting conduit 204. The harvesting conduit is in fluidcommunication with conduits 250 through which the permeate stream may bewithdrawn from the membrane envelope. The portion of the mixed gasstream that does not pass through the membranes flows to a conduit 252through which this gas may be withdrawn as byproduct stream 36. In FIG.33, a single byproduct conduit 252 is shown, while in FIG. 34 a pair ofconduits 252 are shown to illustrate that any of the conduits describedherein may alternatively include more than one fluid passage. It shouldbe understood that the arrows used to indicate the flow of streams 34and 36 have been schematically illustrated, and that the direction offlow through conduits 250 and 252 may vary, such as depending upon theconfiguration of a particular membrane envelope 200, module 220 and/ordevice 10.

In FIG. 35, another example of a suitable membrane envelope 200 isshown. To graphically illustrate that end plates 60 and shell 62 mayhave a variety of configurations, envelope 200 is shown having agenerally rectangular configuration. The envelope of FIG. 35 alsoprovides another example of a membrane envelope having a pair ofbyproduct conduits 252 and a pair of hydrogen conduits 250. As shown,envelope 200 includes feed, or spacer, plates 238 as the outer mostframes in the envelope. Generally, each of plates 238 includes a frame260 that defines an inner open region 262. Each inner open region 262couples laterally to conduits 252. Conduits 250, however, are closedrelative to open region 262, thereby isolating hydrogen-rich stream 34.Membrane plates 242 lie adjacent and interior to plates 238. Membraneplates 242 each include as a central portion thereof ahydrogen-selective membrane 46, which may be secured to an outer frame240, which is shown for purposes of graphical illustration. In plates242, all of the conduits are closed relative to membrane 46. Eachmembrane lies adjacent to a corresponding one of open regions 262, i.e.,adjacent to the flow of mixed gas arriving to the envelope. Thisprovides an opportunity for hydrogen gas to pass through the membrane,with the non-permeating gases, i.e., the gases forming byproduct stream36, leaving open region 262 through conduit 252. Screen plate 234 ispositioned intermediate membranes 46 and/or membrane plates 242, i.e.,on the interior or permeate side of each of membranes 46. Screen plate234 includes a screen structure 210 or another suitable support 54.Conduits 252 are closed relative to the central region of screen plate234, thereby isolating the byproduct stream 36 and mixed gas stream 24from hydrogen-rich stream 34. Conduits 250 are open to the interiorregion of screen plate 234. Hydrogen gas, having passed through theadjoining membranes 46, travels along and through screen structure 210to conduits 250 and eventually to an output port as the hydrogen-richstream 34.

As discussed, device 10 may include a single membrane 46 within shell62, a plurality of membranes within shell 62, one or more membraneenvelopes 200 within shell 62 and/or other separation assemblies 20. InFIG. 36, a membrane envelope 200 similar to that shown in FIG. 34 isshown positioned within shell 62 to illustrate this point. It should beunderstood that envelope 200 may also schematically represent a membranemodule 220 containing a plurality of membrane envelopes, and/or a singlemembrane plate 242. Also shown for purposes of illustration is anexample of a suitable position for guide structures 144. As discussed,structures 144 also represent an example of internal supports 196. FIG.36 also illustrates graphically an example of suitable positions forports 64, 66 and 68. To further illustrate suitable positions of themembrane plates and/or membrane envelopes within devices 10 containingend plates according to the present invention, FIGS. 37 and 38respectively illustrate in dashed lines a membrane plate 242, membraneenvelope 200 and/or membrane module 220 positioned within a device 10that includes the end plates shown in FIGS. 13-14 and 21-25.

Shell 62 has been described as interconnecting the end plates to definetherewith internal compartment 18. It is within the scope of theinvention that the shell may be formed from a plurality ofinterconnected plates 230. For example, a membrane module 220 thatincludes one or more membrane envelopes 200 may form shell 62 becausethe perimeter regions of each of the plates may form a fluid-tight, orat least substantially fluid-tight seal therebetween. An example of sucha construction is shown in FIG. 39, in which a membrane module 220 thatincludes three membrane envelopes 200 is shown. It should be understoodthat the number of membrane envelopes may vary, from a single envelopeor even a single membrane plate 242, to a dozen or more. In FIG. 39, endplates 60 are schematically represented as having generally rectangularconfigurations to illustrate that configurations other than circularconfigurations are within the scope of the invention. It should beunderstood that the schematically depicted end plates 60 may have any ofthe end plate configurations discussed, illustrated and/or incorporatedherein.

In the preceding discussion, illustrative examples of suitable materialsof construction and methods of fabrication for the components ofhydrogen purification devices according to the present invention havebeen discussed. It should be understood that the examples are not meantto represent an exclusive, or closed, list of exemplary materials andmethods, and that it is within the scope of the invention that othermaterials and/or methods may be used. For example, in many of the aboveexamples, desirable characteristics or properties are presented toprovide guidance for selecting additional methods and/or materials. Thisguidance is also meant as an illustrative aid, as opposed to recitingessential requirements for all embodiments.

As discussed, in embodiments of device 10 that include a separationassembly that includes hydrogen-permeable and/or hydrogen-selectivemembranes 46, suitable materials for membranes 46 include palladium andpalladium alloys. As also discussed, the membranes may be supported byframes and/or supports, such as the previously described frames 240,supports 54 and screen structure 210. Furthermore, devices 10 are oftenoperated at selected operating parameters that include elevatedtemperatures and pressures. In such an application, the devicestypically begin at a startup, or initial, operating state, in which thedevices are typically at ambient temperature and pressure, such asatmospheric pressure and a temperature of approximately 25° C. From thisstate, the device is heated (such as with heating assembly 42) andpressurized (via any suitable mechanism) to selected operatingparameters, such as temperatures of 200° C. or more, and selectedoperating pressures, such as a pressure of 50 psi or more.

When devices 10 are heated, the components of the devices will expand.The degree to which the components enlarge or expand is largely definedby the coefficient of thermal expansion (CTE) of the materials fromwhich the components are formed. Accordingly, these differences in CTE'swill tend to cause the components to expand at different rates, therebyplacing additional tension or compression on some components and/orreduced tension or compression on others.

For example, consider a hydrogen-selective membrane 46 formed from analloy of 60 wt % palladium and 40 wt % copper (Pd-40Cu). Such a membranehas a coefficient of thermal expansion of 14.9 (μm/m)/° C. Furtherconsider that the membrane is secured to a structural frame 230 or othermount, or retained against a support 54 formed from a material having adifferent CTE than Pd-40Cu or another material from which membrane 46 isformed. When a device 10 in which these components are operated isheated from an ambient or resting configuration, the components willexpand at different rates. Typically, device 10 is thermally cycledwithin a temperature range of at least 200° C., and often within a rangeof at least 250° C., 300° C. or more. If the CTE of the membrane is lessthan the CTE of the adjoining structural component, then the membranewill tend to be stretched as the components are heated.

In addition to this initial stretching, it should be considered thathydrogen purification devices typically experience thermal cycling asthey are heated for use, then cooled or allowed to cool when not in use,then reheated, recooled, etc. In such an application, the stretchedmembrane may become wrinkled as it is compressed toward its originalconfiguration as the membrane and other structural component(s) arecooled.

On the other hand, if the CTE of the membrane is greater than the CTE ofthe adjoining structural component, then the membrane will tend to becompressed during heating of the device, and this compression may causewrinkling of the membrane. During cooling, or as the components cool,the membrane is then drawn back to its original configuration.

As an illustrative example, consider membrane plate 242 shown in FIG.34. If the CTE of membrane 46 is greater than the CTE of frame member230, which typically has a different composition than membrane 46, thenthe membrane will tend to expand faster when heated than the frame.Accordingly, compressive forces will be imparted to the membrane fromframe 230, and these forces may produce wrinkles in the membrane. Incontrast, if the CTE of membrane 46 is less than the CTE of frame 230,then the frame will expand faster when heated than membrane 46. As thisoccurs, expansive forces will be imparted to the membrane, as theexpansion of the frame in essence tries to stretch the membrane. Whileneither of these situations is desirable, compared to an embodiment inwhich the frame and membrane have the same or essentially the same CTE,the former scenario may in some embodiments be the more desirable of thetwo because it may be less likely to produce wrinkles in the membrane.

Wrinkling of membrane 46 may cause holes and cracks in the membrane,especially along the wrinkles where the membrane is fatigued. In regionswhere two or more wrinkles intersect, the likelihood of holes and/orcracks is increased because that portion of the membrane has beenwrinkled in at least two different directions. It should be understoodthat holes and cracks lessen the selectivity of the membrane forhydrogen gas because the holes and/or cracks are not selective forhydrogen gas and instead allow any of the components of the mixed gasstream to pass thereto. During repeated thermal cycling of the membrane,these points or regions of failure will tend to increase in size,thereby further decreasing the purity of the hydrogen-rich, or permeate,stream. It should be further understood that these wrinkles may becaused by forces imparted to the membrane from portions of device 10that contact the membrane directly, and which accordingly may bereferred to as membrane-contacting portions or structure, or by otherportions of the device that do not contact the membrane but which uponexpansion and/or cooling impart forces that are transmitted to themembrane. Examples of membrane-contacting structure include frames orother mounts 52 and supports 54 upon which the membrane is mounted orwith which membrane 46 is in contact even if the membrane is notactually secured or otherwise mounted thereon. Examples of portions ofdevice 10 that may, at least in some embodiments, impartwrinkle-inducing forces to membrane 46 include the enclosure 12, andportions thereof such as one or more end plates 60 and/or shell 62.Other examples include gaskets and spacers between the end plates andthe frames or other mounts for the membrane, and in embodiments ofdevice 10 that include a plurality of membranes, between adjacent framesor other supports or mounts for the membranes.

One approach to guarding against membrane failure due to differences inCTE between the membranes and adjoining structural components is toplace deformable gaskets between the membrane and any component ofdevice 10 that contacts the membrane and has sufficient stiffness orstructure to impart compressive or tensile forces to the membrane thatmay wrinkle the membrane. For example, in FIG. 33, membrane 46 is shownsandwiched between feed plate 238 and permeate gasket 236, both of whichmay be formed from a deformable material. In such an embodiment and withsuch a construction, the deformable gaskets buffer, or absorb, at leasta significant portion of the compressive or tensile forces thatotherwise would be exerted upon membrane 46.

In embodiments where either or both of these frames are not formed froma deformable material (i.e., a resilient material that may be compressedor expanded as forces are imparted thereto and which returns to itsoriginal configuration upon removal of those forces), when membrane 46is mounted on a plate 242 that has a thickness and/or composition thatmay exert the above-described wrinkling tensile or compressive forces tomembrane 46, or when support 54 is bonded (or secured under the selectedoperating pressure) to membrane 46, a different approach mayadditionally or alternatively be used. More specifically, the life ofthe membranes may be increased by forming components of device 10 thatotherwise would impart wrinkling forces, either tensile or compressive,to membrane 46 from materials having a CTE that is the same or similarto that of the material or materials from which membrane 46 is formed.

For example, Type 304 stainless steel has a CTE of 17.3 and Type 316stainless steel has a CTE of 16.0. Accordingly, Type 304 stainless steelhas a CTE that is approximately 15% greater than that of Pd-40Cu, andType 316 stainless steel has a CTE that is approximately 8% greater thanthat of Pd-40Cu. This does not mean that these materials may not be usedto form the various supports, frames, plates, shells and the likediscussed herein. However, in some embodiments of the invention, it maybe desirable to form at least some of these components from a materialthat has a CTE that is the same as or more similar to that of thematerial from which membrane 46 is formed. More specifically, it may bedesirable to have a CTE that is the same as the CTE of the material fromwhich membrane 46 is formed, or a material that has a CTE that is withina selected range of the CTE of the material from which membrane 46 isselected, such as within ±0.5%, 1%, 2%, 5%, 10%, or 15%. Expressedanother way, in at least some embodiments, it may be desirable to formthe membrane-contacting portions or other elements of the device from amaterial or materials that have a CTE that is within ±1.2, 1, 0.5, 0.2,0.1 or less than 0.1 μm/m/° C. of the CTE from which membrane 46 is atleast substantially formed. Materials having one of the abovecompositions and/or CTE's relative to the CTE of membrane 46 may bereferred to herein as having one of the selected CTE's within thecontext of this disclosure.

In the following table, exemplary alloys and their corresponding CTE'sand compositions are presented. It should be understood that thematerials listed in the following table are provided for purposes ofillustration, and that other materials may be used, includingcombinations of the below-listed materials and/or other materials,without departing from the scope of the invention.

TABLE 1 Nominal Composition Alloy CTE Type/Grade (μm/m/C) C Mn Ni Cr CoMo W Nb Cu Ti Al Fe Si Pd-40Cu 14.9 Monet 400 13.9 .02 1.5 65 32 2.0(UNS N04400) Monet 401 13.7 .05 2.0 42 54 0.5 (UNS N04401) 13.7 .02 1.565 32 2.0 Monet 405 (UNS N04405) Monet 500 13.7 .02 1.0 65 32 0.6 1.5(UNS N05500) Type 304 17.3 .05 1.5 9.0 19.0 Bal 0.5 Stainless (UNSS30400) Type 316 16.0 .05 1.5 12.0 17.0 2.5 Bal 0.5 Stainless (UNSS31600) Type 310S 15.9 .05 1.5 20.5 25.0 Bal 1.1 Stainless (UNS S31008)Type 330 14.4 .05 1.5 35.5 18.5 Bal 1.1 Stainless (UNS N08330) AISI Type14.0 .1 1.5 20.0 21.0 20.5 3.0 2.5 1.0 31.0 0.8 661 Stainless (UNSR30155) Inconel 600 13.3 .08 76.0 15.5 8.0 (UNS N06600) Inconel 60113.75 .05 60.5 23.0 0.5 1.35 14.1 (UNS N06601) Inconel 625 12.8 .05 61.021.5 9.0 3.6 0.2 0.2 2.5 (UNS N06625) Incoloy 800 14.4 .05 0.8 32.5 0.40.4 0.4 46.0 0.5 (UNS N08800) Nimonic 13.5 .05 42.5 12.5 6.0 2.7 36.2Alloy 901 (UNS N09901) Hastelloy X 13.3 .15 49.0 22.0 1.5 9.0 0.6 2 15.8(UNS N06002) Inconel 718 13.0 .05 52.5 19.0 3.0 5.1 0.9 0.5 18.5 UNSN07718) Haynes 230 12.7 0.1 55.0 22.0 5.0 2.0 14 0.35 3.0 (UNS N06002)

From the above information, it can be seen that alloys such as Type 330stainless steel and Incoloy 800 have CTE's that are within approximately3% of the CTE of Pd40Cu, and Monel 400 and Types 310S stainless steelhave CTE's that deviate from the CTE of Pd40Cu by less than 7%.

To illustrate that the selection of materials may vary with the CTE ofthe particular membrane being used, consider a material for membrane 46that has a coefficient of thermal expansion of 13.8 μm/m/° C. From theabove table, it can be seen that the Monel and Inconel 600 alloys haveCTE's that deviate, or differ from, the CTE of the membrane by 0.1μm/m/° C. As another example, consider a membrane having a CTE of 13.4μm/m/° C. Hastelloy X has a CTE that corresponds to that of themembrane, and that the Monel and Inconel 601 alloys have CTE's that arewithin approximately 1% of the CTE of the membrane. Of the illustrativeexample of materials listed in the table, all of the alloys other thanHastelloy X, Incoloy 800 and the Type 300 series of stainless steelalloys have CTE's that are within 2% of the CTE of the membrane, and allof the alloys except Type 304, 316 and 310S stainless steel alloys haveCTE's that are within 5% of the CTE of the membrane.

Examples of components of device 10 that may be formed from a materialhaving a selected CTE relative to membrane 46, such as a CTEcorresponding to or within one of the selected ranges of the CTE ofmembrane 46, include one or more of the following: support 54, screenmembers 212, fine or outer screen or expanded metal member 216, innerscreen member 214, membrane frame 240, permeate frame 232, permeateplate 234, feed plate 238. By the above, it should be understood thatone of the above components may be formed from such a material, morethan one of the above components may be formed from such a material, butthat none of the above components are required to be formed from such amaterial. Similarly, the membranes 46 may be formed from materials otherthan Pd-40Cu, and as such the selected CTE's will vary depending uponthe particular composition of membranes 46.

By way of further illustration, a device 10 may be formed with amembrane module 220 that includes one or more membrane envelopes 200with a support that includes a screen structure which is entirely formedfrom a material having one of the selected CTE's. As another example,only the outer, or membrane-contacting, screen members (such as members216) may be formed from a material having one of the selected CTE's,with the inner member or members being formed from a material that doesnot have one of the selected CTE's. As still another illustrativeexample, the inner screen member 214 may be formed from a materialhaving one of the selected CTE's, with the membrane-contacting membersbeing formed from a material that does not have one of the selectedCTE's, etc.

In some embodiments, it may be sufficient for only the portions of thesupport that have sufficient stiffness to cause wrinkles in themembranes during the thermal cycling and other intended uses of thepurification device to be formed from a material having one of theselected CTE's. As an illustrative example, consider screen structure210, which is shown in FIG. 32. In the illustrative embodiment, thescreen structure is adapted to be positioned between a pair of membranes46, and the screen structure includes a pair of outer, ormembrane-contacting screen members 216, and an inner screen member 214that does not contact the membranes. Typically, but not exclusively, theouter screen members are formed from a material that is less stiff andoften more fine than the inner screen member, which tends to have astiffer and often coarser, construction. In such an embodiment, theinner screen member may be formed from a material having one of theselected CTE's, such as an alloy that includes nickel and copper, suchas Monel, with the outer screen members being formed from conventionalstainless steel, such as Type 304 or Type 316 stainless steel. Such ascreen structure may also be described as having a membrane-contactingscreen member with a CTE that differs from the CTE of membrane 46 morethan the CTE of the material from which the inner screen member isformed. As discussed, however, it is also within the scope of theinvention that all of the screen members may be formed from an alloythat includes nickel and copper, such as Monel, or another materialhaving one of the selected CTE's.

This construction also may be applied to supports that include more thanone screen member or layer, but which only support one membrane. Forexample, and with reference to FIG. 2, the support may include amembrane-contacting layer or screen member 214′, which may have aconstruction like a screen member 214. Layer 214′ engages and extendsacross at least a substantial portion of the face of the membrane, buttypically does not itself provide sufficient support to the membranewhen the purification device is pressurized and in use. The support mayfurther include a second layer or second screen member 216′, which mayhave a construction like screen member 216 and which extends generallyparallel to the first layer but on the opposite side of the first layerthan the membrane. This second layer is stiffer than the first layer sothat it provides a composite screen structure that has sufficientstrength, or stiffness, to support the membrane when in use. When such aconstruction is utilized, it may (but is not required to be) implementedwith the second layer, or screen member to be formed from an alloy ofnickel and copper, such as Monel, or another material having a selectedCTE, and with the membrane-contacting layer, or screen member, beingformed from a material having a CTE that differs from the CTE of themembrane by a greater amount than the material from which the secondlayer is formed. Additionally, the membrane-contacting layer may bedescribed as being formed from a material that does not include an alloyof nickel and copper.

Another example of exemplary configurations, a device 10 may have asingle membrane 46 supported between the end plates 60 of the enclosureby one or more mounts 52 and/or one or more supports 54. The mountsand/or the supports may be formed from a material having one of theselected CTE's. Similarly, at least a portion of enclosure 12, such asone or both of end plates 60 or shell 62, may be formed from a materialhaving one of the selected CTE's.

In embodiments of device 10 in which there are components of the devicethat do not directly contact membrane 46, these components may still beformed from a material having one of the selected CTE's. For example, aportion or all of enclosure 12, such as one or both of end plates 60 orshell 62, may be formed from a material, including one of the alloyslisted in Table 1, having one of the selected CTE's relative to the CTEof the material from which membrane 46 is formed even though theseportions do not directly contact membrane 46.

A hydrogen purification device 10 constructed according to the presentinvention may be coupled to, or in fluid communication with, any sourceof impure hydrogen gas. Examples of these sources include gas storagedevices, such as hydride beds and pressurized tanks. Another source isan apparatus that produces as a byproduct, exhaust or waste stream aflow of gas from which hydrogen gas may be recovered. Still anothersource is a fuel processor, which as used herein, refers to any devicethat is adapted to produce a mixed gas stream containing hydrogen gasfrom at least one feed stream containing a feedstock. Typically,hydrogen gas will form a majority or at least a substantial portion ofthe mixed gas stream produced by a fuel processor.

A fuel processor may produce mixed gas stream 24 through a variety ofmechanisms. Examples of suitable mechanisms include steam reforming andautothermal reforming, in which reforming catalysts are used to producehydrogen gas from a feed stream containing a carbon-containing feedstockand water. Other suitable mechanisms for producing hydrogen gas includepyrolysis and catalytic partial oxidation of a carbon-containingfeedstock, in which case the feed stream does not contain water. Stillanother suitable mechanism for producing hydrogen gas is electrolysis,in which case the feedstock is water. Examples of suitablecarbon-containing feedstocks include at least one hydrocarbon oralcohol. Examples of suitable hydrocarbons include methane, propane,natural gas, diesel, kerosene, gasoline and the like. Examples ofsuitable alcohols include methanol, ethanol, and polyols, such asethylene glycol and propylene glycol.

A hydrogen purification device 10 adapted to receive mixed gas stream 24from a fuel processor is shown schematically in FIG. 40. As shown, thefuel processor is generally indicated at 300, and the combination of afuel processor and a hydrogen purification device may be referred to asa fuel processing system 302. Also shown in dashed lines at 42 is aheating assembly, which as discussed provides heat to device 10 and maytake a variety of forms. Fuel processor 300 may take any of the formsdiscussed above. To graphically illustrate that a hydrogen purificationdevice according to the present invention may also receive mixed gasstream 24 from sources other than a fuel processor 300, a gas storagedevice is schematically illustrated at 306 and an apparatus thatproduces mixed gas stream 24 as a waste or byproduct stream in thecourse of producing a different product stream 308 is shown at 310. Itshould be understood that the schematic representation of fuel processor300 is meant to include any associated heating assemblies, feedstockdelivery systems, air delivery systems, feed stream sources or supplies,etc.

Fuel processors are often operated at elevated temperatures and/orpressures. As a result, it may be desirable to at least partiallyintegrate hydrogen purification device 10 with fuel processor 300, asopposed to having device 10 and fuel processor 300 connected by externalfluid transportation conduits. An example of such a configuration isshown in FIG. 42, in which the fuel processor includes a shell orhousing 312, which device 10 forms a portion of and/or extends at leastpartially within. In such a configuration, fuel processor 300 may bedescribed as including device 10. Integrating the fuel processor orother source of mixed gas stream 24 with hydrogen purification device 10enables the devices to be more easily moved as a unit. It also enablesthe fuel processor's components, including device 10, to be heated by acommon heating assembly and/or for at least some if not all of theheating requirements of device 10 be to satisfied by heat generated byprocessor 300.

As discussed, fuel processor 300 is any suitable device that produces amixed gas stream containing hydrogen gas, and preferably a mixed gasstream that contains a majority of hydrogen gas. For purposes ofillustration, the following discussion will describe fuel processor 300as being adapted to receive a feed stream 316 containing acarbon-containing feedstock 318 and water 320, as shown in FIG. 42.However, it is within the scope of the invention that the fuel processor300 may take other forms, as discussed above, and that feed stream 316may have other compositions, such as containing only a carbon-containingfeedstock or only water.

Feed stream 316 may be delivered to fuel processor 300 via any suitablemechanism. A single feed stream 316 is shown in FIG. 42, but it shouldbe understood that more than one stream 316 may be used and that thesestreams may contain the same or different components. When thecarbon-containing feedstock 318 is miscible with water, the feedstock istypically delivered with the water component of feed stream 316, such asshown in FIG. 42. When the carbon-containing feedstock is immiscible oronly slightly miscible with water, these components are typicallydelivered to fuel processor 300 in separate streams, such as shown indashed lines in FIG. 42. In FIG. 42, feed stream 316 is shown beingdelivered to fuel processor 300 by a feed stream delivery system 317.Delivery system 317 includes any suitable mechanism, device, orcombination thereof that delivers the feed stream to fuel processor 300.For example, the delivery system may include one or more pumps thatdeliver the components of stream 316 from a supply. Additionally, oralternatively, system 317 may include a valve assembly adapted toregulate the flow of the components from a pressurized supply. Thesupplies may be located external of the fuel cell system, or may becontained within or adjacent the system.

As generally indicated at 332 in FIG. 42, fuel processor 300 includes ahydrogen-producing region in which mixed gas stream 24 is produced fromfeed stream 316. As discussed, a variety of different processes may beutilized in hydrogen-producing region 332. An example of such a processis steam reforming, in which region 332 includes a steam reformingcatalyst 334. Alternatively, region 332 may produce stream 24 byautothermal reforming, in which case region 332 includes an autothermalreforming catalyst. In the context of a steam or autothermal reformer,mixed gas stream 24 may also be referred to as a reformate stream.Preferably, the fuel processor is adapted to produce substantially purehydrogen gas, and even more preferably, the fuel processor is adapted toproduce pure hydrogen gas. For the purposes of the present invention,substantially pure hydrogen gas is greater than 90% pure, preferablygreater than 95% pure, more preferably greater than 99% pure, and evenmore preferably greater than 99.5% pure. Examples of suitable fuelprocessors are disclosed in U.S. Pat. No. 6,221,117, pending U.S. patentapplication Ser. No. 09/802,361, which was filed on Mar. 8, 2001, and isentitled “Fuel Processor and Systems and Devices Containing the Same,”and U.S. Pat. No. 6,319,306, which was filed on Mar. 19, 2001, and isentitled “Hydrogen-Selective Metal Membrane Modules and Method ofForming the Same,” each of which is incorporated by reference in itsentirety for all purposes.

Fuel processor 300 may, but does not necessarily, further include apolishing region 348, such as shown in dashed lines in FIG. 42.Polishing region 348 receives hydrogen-rich stream 34 from device 10 andfurther purifies the stream by reducing the concentration of, orremoving, selected compositions therein. In FIG. 42, the resultingstream is indicated at 314 and may be referred to as a product hydrogenstream or purified hydrogen stream. When fuel processor 300 does notinclude polishing region 348, hydrogen-rich stream 34 forms producthydrogen stream 314. For example, when stream 34 is intended for use ina fuel cell stack, compositions that may damage the fuel cell stack,such as carbon monoxide and carbon dioxide, may be removed from thehydrogen-rich stream, if necessary. The concentration of carbon monoxideshould be less than 10 ppm (parts per million) to prevent the controlsystem from isolating the fuel cell stack. Preferably, the system limitsthe concentration of carbon monoxide to less than 5 ppm, and even morepreferably, to less than 1 ppm. The concentration of carbon dioxide maybe greater than that of carbon monoxide. For example, concentrations ofless than 25% carbon dioxide may be acceptable. Preferably, theconcentration is less than 10%, even more preferably, less than 1%.Especially preferred concentrations are less than 50 ppm. It should beunderstood that the acceptable minimum concentrations presented hereinare illustrative examples, and that concentrations other than thosepresented herein may be used and are within the scope of the presentinvention. For example, particular users or manufacturers may requireminimum or maximum concentration levels or ranges that are differentthan those identified herein.

Region 348 includes any suitable structure for removing or reducing theconcentration of the selected compositions in stream 34. For example,when the product stream is intended for use in a PEM fuel cell stack orother device that will be damaged if the stream contains more thandetermined concentrations of carbon monoxide or carbon dioxide, it maybe desirable to include at least one methanation catalyst bed 350. Bed350 converts carbon monoxide and carbon dioxide into methane and water,both of which will not damage a PEM fuel cell stack. Polishing region348 may also include another hydrogen-producing region 352, such asanother reforming catalyst bed, to convert any unreacted feedstock intohydrogen gas. In such an embodiment, it is preferable that the secondreforming catalyst bed is upstream from the methanation catalyst bed soas not to reintroduce carbon dioxide or carbon monoxide downstream ofthe methanation catalyst bed.

Steam reformers typically operate at temperatures in the range of 200°C. and 700° C., and at pressures in the range of 50 psi and 1000 psi,although temperatures outside of this range are within the scope of theinvention, such as depending upon the particular type and configurationof fuel processor being used. Any suitable heating mechanism or devicemay be used to provide this heat, such as a heater, burner, combustioncatalyst, or the like. The heating assembly may be external the fuelprocessor or may form a combustion chamber that forms part of the fuelprocessor. The fuel for the heating assembly may be provided by the fuelprocessing or fuel cell system, by an external source, or both.

In FIG. 42, fuel processor 300 is shown including a shell 312 in whichthe above-described components are contained. Shell 312, which also maybe referred to as a housing, enables the components of the fuelprocessor to be moved as a unit. It also protects the components of thefuel processor from damage by providing a protective enclosure andreduces the heating demand of the fuel processor because the componentsof the fuel processor may be heated as a unit. Shell 312 may, but doesnot necessarily, include insulating material 333, such as a solidinsulating material, blanket insulating material, or an air-filledcavity. It is within the scope of the invention, however, that the fuelprocessor may be formed without a housing or shell. When fuel processor300 includes insulating material 333, the insulating material may beinternal the shell, external the shell, or both. When the insulatingmaterial is external a shell containing the above-described reforming,separation and/or polishing regions, the fuel processor may furtherinclude an outer cover or jacket external the insulation.

It is further within the scope of the invention that one or more of thecomponents of fuel processor 300 may either extend beyond the shell orbe located external at least shell 312. For example, device 10 mayextend at least partially beyond shell 312, as indicated in FIG. 41. Asanother example, and as schematically illustrated in FIG. 42, polishingregion 348 may be external shell 312 and/or a portion ofhydrogen-producing region 332 (such as portions of one or more reformingcatalyst beds) may extend beyond the shell.

As indicated above, fuel processor 300 may be adapted to deliverhydrogen-rich stream 34 or product hydrogen stream 314 to at least onefuel cell stack, which produces an electric current therefrom. In such aconfiguration, the fuel processor and fuel cell stack may be referred toas a fuel cell system. An example of such a system is schematicallyillustrated in FIG. 43, in which a fuel cell stack is generallyindicated at 322. The fuel cell stack is adapted to produce an electriccurrent from the portion of product hydrogen stream 314 deliveredthereto. In the illustrated embodiment, a single fuel processor 300 anda single fuel cell stack 322 are shown and described, however, it shouldbe understood that more than one of either or both of these componentsmay be used. It should also be understood that these components havebeen schematically illustrated and that the fuel cell system may includeadditional components that are not specifically illustrated in thefigures, such as feed pumps, air delivery systems, heat exchangers,heating assemblies and the like.

Fuel cell stack 322 contains at least one, and typically multiple, fuelcells 324 that are adapted to produce an electric current from theportion of the product hydrogen stream 314 delivered thereto. Thiselectric current may be used to satisfy the energy demands, or appliedload, of an associated energy-consuming device 325. Illustrativeexamples of devices 325 include, but should not be limited to, a motorvehicle, recreational vehicle, boat, tools, lights or lightingassemblies, appliances (such as a household or other appliance),household, signaling or communication equipment, etc. It should beunderstood that device 325 is schematically illustrated in FIG. 43 andis meant to represent one or more devices or collection of devices thatare adapted to draw electric current from the fuel cell system. A fuelcell stack typically includes multiple fuel cells joined togetherbetween common end plates 323, which contain fluid delivery/removalconduits (not shown). Examples of suitable fuel cells include protonexchange membrane (PEM) fuel cells and alkaline fuel cells. Fuel cellstack 322 may receive all of product hydrogen stream 314. Some or all ofstream 314 may additionally, or alternatively, be delivered, via asuitable conduit, for use in another hydrogen-consuming process, burnedfor fuel or heat, or stored for later use.

INDUSTRIAL APPLICABILITY

The invented hydrogen purification devices, components and fuelprocessing systems are applicable to the fuel processing and otherindustries in which hydrogen gas is produced and/or utilized.

It is believed that the disclosure set forth above encompasses multipledistinct inventions with independent utility. While each of theseinventions has been disclosed in its preferred form, the specificembodiments thereof as disclosed and illustrated herein are not to beconsidered in a limiting sense as numerous variations are possible. Thesubject matter of the inventions includes all novel and non-obviouscombinations and subcombinations of the various elements, features,functions and/or properties disclosed herein. Similarly, where theclaims recite “a” or “a first” element or the equivalent thereof, suchclaims should be understood to include incorporation of one or more suchelements, neither requiring nor excluding two or more such elements.

It is believed that the following claims particularly point out certaincombinations and subcombinations that are directed to one of thedisclosed inventions and are novel and non-obvious. Inventions embodiedin other combinations and subcombinations of features, functions,elements and/or properties may be claimed through amendment of thepresent claims or presentation of new claims in this or a relatedapplication. Such amended or new claims, whether they are directed to adifferent invention or directed to the same invention, whetherdifferent, broader, narrower or equal in scope to the original claims,are also regarded as included within the subject matter of theinventions of the present disclosure.

We claim:
 1. A fuel processing assembly, comprising: ahydrogen-producing region adapted to produce a mixed gas streamcontaining hydrogen gas and other gases from a feed stream; an enclosuredefining an internal compartment; wherein the enclosure includes a pairof end plates and a shell portion that extends at least partiallybetween the end plates to define at least a portion of the enclosure,wherein the enclosure is adapted to receive at least a portion of themixed gas stream and to separate the mixed gas stream, via apressure-driven separation process, into at least one product stream andat least one byproduct stream, and further wherein the enclosure furtherincludes means for removing the at least one product stream from theinternal compartment and means for removing the at least one byproductstream from the internal compartment; at least one hydrogen-selectivemembrane supported within the compartment, wherein the at least onehydrogen-selective membrane includes a first surface adapted to becontacted by the mixed gas stream and a permeate surface generallyopposed to the first surface, wherein the product stream is formed froma portion of the mixed gas stream that passes through the at least onehydrogen-selective membrane to the permeate surface, and the byproductstream is formed from a portion of the mixed gas stream that does notpass through the at least one hydrogen-selective membrane; and a supportstructure adapted to support the at least one hydrogen-selectivemembrane within the compartment, wherein the support structure has adifferent composition than the at least one hydrogen-selective membrane,is formed from a composition that includes an alloy comprising nickeland copper, and has a coefficient of thermal expansion that is withinapproximately 10% of the coefficient of thermal expansion of the atleast one hydrogen-selective membrane.
 2. The assembly of claim 1,wherein the support structure has a coefficient of thermal expansionthat is within 5% of the coefficient of thermal expansion of the atleast one hydrogen-selective membrane.
 3. The assembly of claim 2,wherein the support structure has a coefficient of thermal expansionthat is within 2% of the coefficient of thermal expansion of the atleast one hydrogen-selective membrane.
 4. The assembly of claim 1,wherein the support structure has a coefficient of thermal expansionthat is less than the coefficient of thermal expansion of the at leastone hydrogen-selective membrane.
 5. The assembly of claim 4, wherein thesupport structure has a coefficient of thermal expansion that is greaterthan approximately 13 μm/m/° C.
 6. The assembly of claim 4, wherein thesupport structure is metallic.
 7. The assembly of claim 1, wherein theat least one hydrogen-selective membrane is at least substantiallyformed from a palladium alloy that includes approximately 40 wt %copper.
 8. The assembly of claim 1, wherein the at least onehydrogen-selective membrane has a generally planar configuration.
 9. Theassembly of claim 1, wherein the support structure is nothydrogen-selective.
 10. The assembly of claim 1, wherein the supportstructure includes at least one screen member.
 11. The assembly of claim1, wherein the support structure includes a plurality of screen members.12. The assembly of claim 11, wherein the plurality of screen membersincludes at least one screen member that forms at least a portion of thesupport structure, and further wherein the plurality of screen membersincludes at least one screen member that does not contact the at leastone hydrogen-selective membrane.
 13. The assembly of claim 1, whereinthe enclosure is at least substantially formed from an alloy of nickeland copper.
 14. The assembly of claim 1, wherein the enclosure has acoefficient of thermal expansion that is less than 16 μm/m/° C.
 15. Theassembly of claim 1, wherein the enclosure has a coefficient of thermalexpansion that is less than the coefficient of thermal expansion of theat least one hydrogen-selective membrane.
 16. The assembly of claim 1,wherein each of the end plates includes a perimeter region, and furtherwherein at least a portion of the shell portion is integrally formedwith a first one of the end plates and projects from the perimeterregion thereof generally toward a second one of the end plates.
 17. Theassembly of claim 16, wherein the shell portion includes an end portiondistal the first one of the end plates that is adapted to form an atleast substantially fluid-tight interface with a sealing region of thesecond one of the end plates.
 18. The assembly of claim 16, wherein theshell portion is a first shell portion that is integrally formed withthe first one of the pair of end plates, wherein the enclosure furtherincludes a second shell portion that is integrally formed with thesecond one of the end plates and which extends generally toward thefirst one of the end plates.
 19. The assembly of claim 18, wherein theshell portions include end regions that are adapted to collectively forman at least substantially fluid-tight interface.
 20. The assembly ofclaim 19, wherein the assembly further includes at least one seal memberextending between the end regions.
 21. The assembly of claim 16, whereinthe enclosure includes only a single interface between the pair of endplates and the shell portion.
 22. The assembly of claim 16, wherein theat least one hydrogen-selective membrane includes a pair ofhydrogen-selective membranes that are oriented such that the pair ofhydrogen-selective membranes are spaced-apart from each other with theirpermeate surfaces generally facing each other to define a membraneenvelope with a harvesting conduit extending between the permeatesurfaces, and further wherein the product stream is formed from theportion of the mixed gas stream that passes through the membranes to theharvesting conduit, with the remaining portion of the mixed gas streamwhich remains on the first surface of the membranes forming at least aportion of the byproduct stream.
 23. The assembly of claim 22, whereinthe support structure extends within the harvesting conduit.
 24. Theassembly of claim 23, further comprising a plurality of membraneenvelopes.
 25. The assembly of claim 23, wherein the pair ofhydrogen-selective membranes comprise an alloy of palladium andapproximately 40 wt % copper.
 26. The assembly of claim 1, incombination with a fuel cell stack adapted to receive at least a portionof the product stream.
 27. The assembly of claim 26, in combination withat least one assembly adapted to reduce the concentration of any carbonmonoxide present in the product stream.
 28. The assembly of claim 1,wherein the hydrogen-producing region includes a catalyst adapted toproduce the mixed gas stream via steam reforming of a feed stream thatincludes water and at least one carbon-containing feedstock.
 29. Theassembly of claim 28, in combination with a fuel cell stack adapted toreceive at least a portion of the product stream.
 30. The assembly ofclaim 29, in combination with at least one assembly adapted to reducethe concentration of any carbon monoxide present in the product stream.31. A hydrogen purification device, comprising an enclosure defining aninternal compartment; wherein the enclosure is adapted to receive amixed gas stream comprising hydrogen gas and other gases and having atemperature of at least 300° C. and a pressure of at least 100 psi,wherein the enclosure includes means for receiving the mixed gas streaminto the internal compartment, means for removing a byproduct streamfrom the internal compartment and means for removing a product hydrogenstream from the internal compartment; at least one hydrogen-selectivemembrane supported within the compartment, wherein the at least onehydrogen-selective membrane is formed from an alloy of palladium andcopper and has a coefficient of thermal expansion, wherein the at leastone hydrogen-selective membrane includes a first surface adapted to becontacted by the mixed gas stream and a permeate surface generallyopposed to the first surface, and further wherein the product hydrogenstream is formed from a portion of the mixed gas stream that passesthrough the at least one hydrogen-selective membrane to the permeatesurface, and the byproduct stream is formed from a portion of the mixedgas stream that does not pass through the at least onehydrogen-selective membrane; and a membrane-contacting structure that isin contact with at least one of the first or the permeate surfaces ofthe membrane, wherein the membrane-contacting structure is selected tohave a coefficient of thermal expansion that is sufficiently close to orequal to the coefficient of thermal expansion of the at least onehydrogen-selective membrane such that upon thermal cycling of the devicewithin a temperature range of at least 200° C. the membrane-contactingstructure is adapted to not impart wrinkle-inducing forces to the atleast one hydrogen-selective membrane.
 32. The device of claim 31,wherein the membrane-contacting structure includes an alloy comprisingnickel and copper.
 33. The device of claim 31, wherein themembrane-contacting structure has a coefficient of thermal expansionthat is the same as or less than the coefficient of thermal expansion ofthe at least one hydrogen-selective membrane.
 34. The device of claim31, wherein the enclosure is formed from one or more materials selectedsuch that upon thermal cycling of the device within the temperaturerange the enclosure does not impart wrinkle-inducing forces to the atleast one hydrogen-selective membrane.
 35. The device of claim 34,wherein the enclosure includes an alloy comprising nickel and copper.36. The device of claim 35, wherein the enclosure has a coefficient ofthermal expansion that is the same as or less than the coefficient ofthermal expansion of the at least one membrane.
 37. The device of claim31, wherein the at least one hydrogen-selective membrane is formed froman alloy of palladium and approximately 40 wt % copper.
 38. The deviceof claim 31, in combination with a fuel processing assembly that isadapted to receive a feed stream and to produce the mixed gas streamtherefrom.
 39. The device of claim 38, wherein the fuel processingassembly includes at least one reforming catalyst bed and furtherwherein the feed stream contains water and a carbon-containingfeedstock.
 40. The device of claim 39, wherein the at least onereforming catalyst bed and the enclosure are at least partially housedwithin a common shell.
 41. The device of claim 38, in furthercombination with a fuel cell stack adapted to receive at least a portionof the product hydrogen stream and to produce an electric currenttherefrom.
 42. The device of claim 41, further comprising an assemblyadapted to reduce the concentration of any carbon monoxide present inthe product hydrogen stream.
 43. The device of claim 31, in furthercombination with a fuel cell stack adapted to receive at least a portionof the product hydrogen stream and to produce an electric currenttherefrom.
 44. The device of claim 43, further comprising an assemblyadapted to reduce the concentration of any carbon monoxide present inthe product hydrogen stream.